I think the Blue Ocean and Modern Audiences are to blame. They do not play what they like, or do things they dislike or pretend to like something, only because a popular person does or it's popular in the moment. It's due to outsourcing their whole entire mind to the internet and personalities and E-Celebs rather than thinking for themselves or just finding what they like despite the fact it may not be popular like you mentioned. They barely use their minds and for that they are the worst.
As for these niches like Games, Anime, Hentai, Manga, etc. I think the best thing possible that can be done is to push these Blue Ocean types into other things. For example.
Video Games > Move them into Mihoyoverse(China) or Blue Archive Nexon with Gacha(South Korea) which has been happening recently or to West with POE2 with Live Service Games. A lot of them are casuals and love low effort games, South Korea and China are very much into that. Korea is Fanservice heavy, China is not(depending on if it's Non-Mainland). This will push a lot of those "I hate Fanservice, but i play games that are fanservice heavy" types out of Japanese Circles.
Anime/Manga move them into Manhwa and Gacha.
If we could push the Blue Ocean, Fake Japanese Fans, and even the unironic fence sitters who pretend to like Japanese Games but like to criticize it for Fanservice into China and South Korea it would be much better for us all. Yes the popularity of Japanese Content would be lower, but then it would go back to people who like Japanese Entertainment for what it is with Fanservice heavy, great story, and nice character designed content. Not these fake fans who buy things, then whine because it's not what they like. Also speaking of Sony, I think the whole reason the big budget AAA, Graphics Max, everyone will pay 70$ has been dying, just because American's are very price conscious and are saying that it is a lot of money, and would rather go to Gacha and Live Services for a lot less money as it's barely much money and time investment for them to get into for 30 minutes to an 1 hour a day or so. Plus you also have Call Of Duty losing it's exclusivity and Microsoft owns it which means everyone is going to use it on Gamepass than going to go on Sony platforms. Basically Sony is in trouble because they relied heavily on exclusivities and thought that they could survive on Live Services, when those services work beyond them.