Sony Executive Weighs in on the Possibility of a Future Release of a PS4 With Improved Performance

[Azuren]

It also seems like people are misunderstanding what's being said here:

The implication is that there wouldn't be a single game that couldn't run on both versions of the console. It's just that the game would have more FPS and/or higher resolution on one version. Your copy of Bloodborne would work on both, but it would be 4K on the hypothetical "PS4K".