It would be ridiculous for Sony to make such a move. Even if backwards compatibility worked they wouldn't sell a whole lot. It's been too soon since the pro, and that hasn't sold much. The system wouldn't be much better than the Scorpio, might as well wait a few years to run 4k games incredibly smoothly. If there were ps5 exclusives they would be separating their fanbase. Not a good move. But they'll do what they want. If it were released next year it would seem like a desperate move to compete with the Scorpio.