Well obviously we'll still see some small differences but i don't expect one version to be 60fps and the other 30fps for example.
Adrian Chmielarz confirmed that multiplatform devs goal is not to push the strongest platform to it limits but instead meat a common target that will make both versions look more or less the same.
Well that big of a framerate difference wouldn't happen even if the dev WAS trying, I can't imagine. The PS4 isn't THAT significantly more powerful than the Xbox One
But we are talking easily that if a game is struggling to hit 30fps on XBO, it'll easily be rock solid on PS4.
And, people had that same goal last gen, sublimit, and multiplatform games across PS3 and 360 were frequently quite superior on the 360. The differences were often fairly large, even so far as to be different resolutions on the various platforms.