Since B/C is going to be industry standard going forward, and across multiple form factors at that, I don't really think Sony has a choice if they want to remain a player in this space.
There have been a lot of signs that PS5 will have B/C. I think the only question now is how far will it go. Sony will have to move away from Cell/Nvidia based servers for PS3 games on PS Now. That will likely mean PS3 games will end up emulated on Epyc/Radeon based servers. This will be the same tech we have in PS5, so there is really no reason PS5 should not include PS3 B/C as well.
Then theire is the next gen Phone/Portable as well. That will need access to PS3 and PS4 titles as well. Sony could win big if they announce all of your Digital PS3 and PS4 titles will be playable on PS5 and PS5 Phone day one.
What PS5 phone?