I believe the wrong way of thinking about current FF situation presumes FF flopping is a Sony/Playstation problem rather than a Square problem. Playstation userbade has been stable and JRPGs still selling the best there. I'll go as far and say FF XVI was saved by Sony timed exclusivity to cover development costs
The debate about FF going multiplat is strange because it presumes FF fandom don't buy Playstation hardware to play FF. The absolute majority of people who wants to play FF will buy a Playstation, it has been the case for the last 20 years
I'm not saying Square is wrong for doing multiplat releases. Being multiplat is a good thing to build a new fandom, since FF fandom is aging
But Every JRPG that experience fandom growth in popularity starts selling better first at Playstation and just then get multiplatform treatment. If the franchise is not growing on PS5 why would it suddenly start growing elsewhere?