The PS4 Neo is basically the same console but with much higher specs. Once a game is optimized for PS4 it will automatically run better without much if any modifications on the PS4 Neo. For example they may need just to uncap/unlock the frame rate and push the resolution to a constant 1080p if needed. Then the devs can do a second round of optimization just for the new console.
It's more likely that the games that will not fully exploit the console potential will be the ones in the Neo.







