Comment by lxgr

There was no backwards compatibility between the PS3 and PS4 whatsoever (except for PS Plus allowing cloud-based game streaming of some PS3 titles), and Sony survived that as well.

What they did was offer some old PS2 games for purchase, though, which allowed them to tap into that very large back catalog. I could see something like this happen for a hypothetical Intel PS6 as well (i.e. skipping PS5 backwards compatibility and tapping into the large catalog of PS4 and PS4/PS5 games).