Will genres go into decline after a peak? Sure. But it's pretty much gurenteed something will be worked on and released now and again, unless it's something very niche but in that case there's probably only a handful of examples regardless.
What bothers me is the person(s) peddling this have no fucking proof, or assume gamers or a certain crowd of gamers/people are that stupid. The horror genre is thriving
in all sectors of gaming! Did you idiots assume no one knew, nor heard about
Dead Space Remake or
RE4Remake already out on store shelves? Are you grifting jackasses hoping the common gamer didn't know about Steam or the indie horror titles released on almost all the consoles?! Hell, the Switch and PS4/PS5 get more of the horror indie titles than the XBOX! Screw off, and throws yourselves off a bridge! If you got nothing important to say, just "trolling", or an asshole who hates a specific genre, sit your ass down, shut up, and let real people talk about genres that are breathing or doing fine with their respective audiences.