Square Enix just recently held a financial results briefing for the fiscal year ending March 2020. Over in Japan, the developer/publisher confirmed that all their new games will be available for both current and next gen consoles.
After the main briefing, Square Enix president and representative director, Yosuke Matsuda, answered media questions. When asked what Square's thinking was towards next gen consoles, Matsuda confirmed that Square Enix plans to "make our new titles available for both current and next-generation consoles."
"The next-generation consoles will have backward compatibility, so we plan for the time being to make our new titles available for both current and next-generation consoles," Matsuda said. "It will therefore be somewhat farther down the road that we release titles exclusively for the next-generation consoles."
From this statement, all signs would seem to point to Final Fantasy 7 Remake being made available for PlayStation 4, as well as PlayStation 5. Matsuda's statement also makes it seem like it'll be a fair while before we start seeing next-generation exclusive games, from Square Enix at least.
Elsewhere in Square Enix's upcoming portfolio, People Can Fly's Outriders has already been confirmed for next generation consoles. Marvel's Avengers will release for Xbox One and PS4 in September 2020, and Matsuda's comments would seem to point to the Marvel game also coming to next generation consoles.
Speaking of Final Fantasy 7 Remake, there's not long to go until part one of the remake releases on April 10, 2020. Square Enix recently confirmed that the second part of the remake is well into development, but it remains to be seen which consoles the second part of the remake will release on.