That depends on the game developers. Some games will be patched, some wont. The games without any patches wont receive any improvements.

Rise of the tomb raider for example, ps4pro users will be given options:
1) uprender the game to 4k for those with 4k tv
2) 1080p same graphica setting with normal ps4 but at higher frame rate (>45-60 fps instead of the normal version's 30fps lock)
3) 1080p 30fps lock but with bumped up graphics similar to pc's max settings.

So yea, this is all depending on the game developers