So, the funny thing about that is, they finally admit that their PS4 launch lineup was crap and now they do the "the best .... ever"-thing (just like MS).
Well, never expected the next God of War for PS4. But it might still come if PS4 sales remain high while the PS5 is almost not available. They can't really produce more (because the fabs and resources are currently just not available). Sony could just not predict the special case of a worldwide pandemic whey they startet the projects.
But after all, I'm still not thinking that a PS4 release would really hurt those games.
E.g. from a typical PS4 game, 1080p 30fps => 4k 60fps it is 8x the power needed (8x on GPU side and around 2x on CPU side). So even if they don't target 4k on PS5 they can still lower the res on PS4 and reduce detail. Yes the HDD to SSD thing might get a problem, but decreased asset quality might also prevent problems there. Maybe even ports by other developers (like nixxes) are possible.