I feel like PS5 needs a very attractive pricepoint, which is almost impossible considering how expensive the PS4 still is.
And it need one absolutely must have Japan-focused launch title. Like a Monster Hunter World 2 or a complete version of FFVII Remake. Which is also something I would categorize as almost impossible.
I hope the PS5 can at least sell as well as the PS4 but it could be a rocky road.
Late ports of MHW & FF7R are possible. I dont think we will see many next-gen exclusives for awhile, most games will be cross-gen for the first 1-2 years.
I don't think late ports are enough. They sell rather poorly in Japan.
PS5 needs a killer app but I have no idea what it could be.