People who think X1 will achieve parity with PS4 on a technical level are just setting themselves up for disappointment. The question is how small they can make the gap, but I think it'll be appreciable on a technical level. That doesn't mean the X1 versions of multi-platform games won't be "good enough" for most people.
The relevance of Digital Foundry comparisons for console warring is pretty much going to be nil, because PS4 is going to win every single time. Now, just doing the comparisons for curiosities sake could be interesting, so I'll still read them, but I have a feeling the number of hits they receive is going to be a lot smaller. There won't be much for people to argue and bicker about.