The Persona series is probably the biggest niche series ever. P5 will be just fine.
I hope so.
Atlus kind of has a difficult situation to deal with. They could just do P4 again except make it even more anime and it'd probably be extremely popular among fans and critics (though some might reject it). Personally, that would be where I'd give up on the series for good.
Atlus can also do something crazy and completely change the formula. Make a transition as big as P2 was to P3. It'd be insane to see what they could come up with, but if they abandoned the waifu pandering and social links, people would despise it for getting rid of that feature (unless its replaced with a similar mechanic in some way). It won't bomb financially, but people could hate it because people hate change in their video games. A lot of them don't even understand that social links and waifus weren't always a thing in Persona games.
That new "how would you improve Persona 5" thread was a perfect example where a majority of people thought I was talking about making it more like SMT4 instead of making it more like P2.
Yeah.. There's quite a lot they could do.. would they revamp everything or just stick with what works. with the dark grim theme it seems like it'll be more akin to p3 or older? It's a possibility.