So is persona no longer niche cause P4G broke 1.7 mil and p5 broke 1 mil
I don't think so. Constant 1 mil is not enough. Constant 3 mil plus is more like it. Metroid is niche, probably one of the more popular niche franchises but still niche. It always breaks 1 mil usually breaks 2 but never breaks 3 mil.
The Persona series ain't niche anymore either. Million-seller games aren't niche.
The JRPG genre ain't niche per se... or are the Final Fantasy and Dragon Quest series also niche?