As soon as they indicated Rebirth would have a shorter exclusivity window the amount of players who would wait for the PC version increased. There are people who own a PS5 but decided to wait for PC for 4K60 and mods. So their sales are PS5 only or people willing to double dip.
Now it's definitely not going to come out June 1st on the dot, but the exclusivity ends in two weeks. If the Steam version hits by fall the overall sales will meet expectations but their public announcement was basically staring Sony in the face and saying PS5 numbers are not enough, what you paid for exclusivity was not enough.