My bet is that you will eventually see it for NextBox somewhere down the line. Or in worst case scenario, just like it happened with the other announcement of Final Fantasy 8 Remastered, you can expect an Xbox release for sure in a decade or two decades from now.
Nope, because Square can now sell it to people for PS4 and then sell it for PS5 and there will be people who will buy it twice. $$$$$$
Or they can just inserts PS4 disc into PS5 and they are good to go.