The gap between the PS4/X1 isn't likely to grow much larger for the moment. The area the PS4 excels at the most compared to the X1 is its much larger GPGPU capabilities, but we are unlikely to see many take full use of it for a few years. I'm pretty sure The Order is utilizing soft body physics though, which could be amazing, but we haven't had a good look at that yet.
Both the PS4 and X1 should see quite a nice visual jump at E3 though. We are moving out of the "launch period", so the visuals will be less rushed and the developers will have had plenty of time with the final builds of their console (unlike previously, when Killzone for example was being made with the belief that the PS4 would have 4GB of RAM, not 8GB).
Should be a fun E3 ^^
