Y'know, I've been through a bunch of Touhou-is-dying doomposts since the time of Kantai Collection's rise, Touhou getting to Steam, Touhou localisation, and Touhou finally getting gacha games and the linked post kinda gives me similar vibes. There is, however, a big glaring issue with the post in question : it talks about past things and how things were, and does not take in consideration the new things that weren't there before.
On the comiket side of things, new series DO get traction, and some at a fast rate and in abundant quantities. That's cuz artists and creators jump into the hottest-new-thing bandwagon, and for good reason. Creating stuff takes time and effort, would you like your fanwork to be available for a somewhat restricted audience or a fast growing one ? It's more interesting for the artists to go for the second option tbh. As for the IP they'll create for, say the gachas for example, this may sound like a bad generalisation, but compared to Touhou the source materials really have a lot of horny bait and stuff : you got voice acting of all kinds, chara designs going from cute to sexy, more sexually suggestives themes, and that's on top of the gameplay they have : if lots of people come for that, then that's just what most people want. Touhou is too prude, too old fashioned, no voice acting, questionable ZUNart, difficult gameplay and too much character and worldbuilding to jump into : in its early days Touhou was UNIQUE in the aspect where it had pretty much 99% female cast, but that niche is pretty much overcrowded these days, and I think an IP that is flashy, sexy, and pumps content at a MUCH FASTER RATE THAN FREAKING ONCE A YEAR is obviously gonna attract the crowds ... and where the crowds be, the artists looking for a break will come too. Ask yourself this : do you want Touhou to COMPETE with IPs that's got qualities (more lewd and more teasing for example) that are absent in Touhou ? Cuz in so doing would require a MASSIVE transformation and changes that might actually not be wanted. When it comes to the Comiket numbers, it's something outside of anyone's control (besides ZUN, who can transform 2hu into a cunnige if he so feels inclined).
As for the community being atomized, honestly, I don't believe it's an issue. People have different preferences even within the fandom, and the ones that have the same taste gather together. What the linked post fails to notice is the fact that within these various mini-communities, things still happen : an excellent exemple for the danmaku games community for example, is the yearly Touhou World Cup, fairly recent but a global Touhou competion featuring basically ALL the most skilled Touhou players from Japan, China, and the rest of the world : there's literally a relatively new YEARLY GLOBAL EVENT THAT'S ORGANIZED BY THE COMMUNITY that was never there in the past (heck, we're in the period of the qualifiers for this year's TWC right now) AND even got mentionned in one of the Touhou Station radio show a while back. The community can't be doing THAT badly if it still can pull a grassroot concerted effort like that. Not to mention the possibility of people from these OTHER communities discovering touhou through them (I know a bunch of people who discover Touhou through Steam fortress videos with Touhou music for example)
And there are many other examples too : in a short while there's gonna be Touhoufest, there is the periodic Touhou fangame jam, and the fact that off late, a new culture surrounding Fumos has seen rise (and quite honestly here to stay as an ersatz of the Yukkuri that the japanese have), the fact that Touhou apparently has a growing popularity among Japanese, uhhh, preschoolers(?) or something (at any rate young school kids), various 2hu collab which keeps getting a rerun (for example Atre, that maid collab whose name I forgot, initial D, some others (can't really keep track of Japan-only happenings)) : these were held by serious companies, not doujin efforts : if they were not a hit (financially), why rerun ? And let's not talk about the whole Yukkuri copyright attempt fiasco from a while back (Yukkuri have sort of grown outside of Touhou in Japan, but Yukkuri Reimu and Yukkuri Marisa are still their main figureheads).
Vtubers playing Touhou has brought some attention from their audience to this series too ; and the approach from the way of doing things in Touhou 14.5 (where circles were brought in to make music) and Touhou 19 (where other people (Unabara Iruka and ZUN's wife) made the sprite assets for the game is definitely a step towards an improvement for future works : ZUN mainly reuse stuff, which is not exciting at all, so the notion of other talents contributing to what we have is always interesting, even if unlikely.
As for the game's balancing, we can elaborate on this in another topic, but it's generally not an issue for the casual players who's gonna bomb and use gimmicks : people have ALWAYS whined about Touhou games balance SINCE TD (UFO too prolly but I'm gonna be generous), yet the fact is that new games don't delete the old ones from existence : there are STILL people playing older games, be it for scoring purposes, or to get the LNN run that'll cement their name in the player community, and people STILL manage to come up with new strategies (yet again, Touhou World Cup) despite all the years : there are people who will hate on the new games, but there are ALSO those who are absolutely into them. I myself love UFO a lot (My fav game), but it's Touhou 18 that I have 1cc'd Lunatic more than a dozen of times, and that regardless of whatever balancing issue it may or may not have. Criticisms happen, some people just can't take it when it comes to their favorite magical girl series, but so long as there remains a core of superplayer base who dedicate themselves to the games, the games will live on. Besides, the average Touhou fan will get the mainline games just because they're mainline ones, and the fanartists and music arrangers will generally make some content related to the new stuff.
And the point about Len'en just straight up doesn't make sense, for the pure and simple reason that it's not as succesfull as Touhou is. Besides all of the superplayers that I've heard comment on that series *absolutely* rail on its balancing too, so no idea what the Len'en part is about.
I've read a simple comment in danbooru back when Kancolle was gaining traction and the whole "it's the Touhou killer" or "Touhou's dying" were way more common than these days. Basically, it said that if Touhou was gone just because of the new hot thing, then that's just all its fandom was worth : I agree, and the fact that people still do Touhou stuff despite the abundance of the unarguably attractive IP and series is plenty evidence that things are fine.
We also have a rocky venture into the realm of mobile games which, while divisive for the community, has got to be have introduced people foreign to the series to Touhou (especially Danmaku Kagura when it was on mobile). We live in a time where more people are aware of Touhou, and lack of fanworks popping can be attributed to potential creator's priorities ...
And on some of the talk about community, I personally am not super familiar with how community dramas and relationships go in general in this fandom (I can have fun by myself and graze past the dramas), but if we're gonna be honest, the ONLY groups that are MOST important are the people who CREATE stuff like music arranges, videos, models, fanarts, fanbook and what have you on one side ; and the TRANSLATORS (god bless) who bring all these goodies to our stinky little selves. This might sound mean or elitist, but I think anything going on in the community that doesn't lead to these people (the fanworks people and the translators) leaving the community is just random noise tbqhwy (sorry poo poo posters). I think the community at large should just not make itself be *too* toxic or else the actual real people who do actual real work are might leave.
But anyway, for me, the problem Touhou face is twofold, none of which we can do anything about YET also show signs of, uhh, attempt at impreovement :
1/ The first one is Time that passed and the times we're in : nothing can be done about this. The circles and fanartists from lie 10 or 15 years ago have their life too and can't be doing doujin works forever, they need a more consistent way of supporting themselves. It's reasonable if people focus on what they have going. But as for the new blood ? Like I said, if what entice people (and the artists that go after them) is the flashy, sexy, often updated brand of entertainment, then there ain't much Touhou can't do. Community involvement is tough to maintain when you get new content ONCE PER FREAKING YEAR and manga discussions on a MONTHLY BASIS AT BEST. Best thing to do is support the various artists best we can. And not be jerks about whatever.
2/ ZUN's attitude : he is easygoing. A bit too much. He himself said in a Touhou Station show that Tsukasa's low firepower in UDoALG is due to a bug yet he hasn't fixed it ... furthermore, the way his writing goes in the current ongoing mangas is HORRENDOUSLY SLOW for one while just another slice of life with an uncertain theme for the other. Are people who run into these manga gonna go fall in love or get very curious about the series ? Doubtfull. Making a Touhou site is cool and all, but it doesn't do much for people who are already into the series. I think the sheer slowness of content dripping is what makes people seek excitement elsewhere. Can't do anything about that cuz that's who just who ZUN is.
At at any rate, it's a waste of time and energy to panic other something that can't be controlled. If the graphics and figures of new-hot-series-getting-more-places-in-Comiket is scary, know Kemono park was pretty massive there too a few years ago before somewhat disappeearing from the common internet user's memory. Things can blow up and just pass away, or can even simply stay there strongly too. Why be insecure over the rise of other series, it's not like they erase what Touhou's got going for it ...
I also don't believe commercialization to be a concern cuz Touhou stuff (and ALL the popular franchises) are plenty commercial anyway : whatcha think all these figurines, posters, fumos and whatever derivative products are ? Even the matter pertaining to reselling has been happening for well over a decade now (unknown flower mesmerizing journey being the worst example), a decade old problem can hardly be an issue, can it ? Not to mention the presence of Steam and Spotify (yes, yes, poor physical copies collectors are gonna need to take the backseat on this one)
Anyway, for the short of it, the linked post is probably a sincere worrypost rather than a doompost, but it just lazer focuses on what weaknesses and issues there are rather than the strenghts and boons we enjoy.
Touhou's gonna continue until ZUN's like "nahhh", honestly. Maybe 2hu's reclining for a bit, maybe not, but no need to fret over what you can't control
Nothing ever happens in these "Touhou is dyeieng" discussions ...