No confirmation about FFXVII will be landed on which platform after that.
Sony has confirmed that <Final Fantasy XVI> will be exclusive for PS5 for only six months. In the latest video introducing the DualSense controller, Sony showcased various PS5 titles including <Final Fantasy XVI> where the footnote reads "Final Fantasy XVI anticipated Summer 2023, PS5 exclusive for six months."
It is unclear which platform will the game go to following this exclusivity period. The Final Trailer for <Final Fantasy VII Remake Intergrade> was also listed as PlayStation 5 exclusivity period for at least six months, but it only came to PC.
Also, the same ad featured <Forspoken>, another upcoming title for Square Enix which will be exclusive for at least 2 years after its release. Yet there's a key difference spotted by DualShockers is that <Forspoken> is coming to PC at launch, meaning its 2-year exclusivity period must be referring to Xbox.