back_by_demand :
The difference between consoles in terms of CPU will change, I have no doubt. The 360 had several refreshes so I fully believe the XB1 will be able to do full 4K gaming. At the moment though the number of people that own 4K TVs isn't high enough to warrant doing it. So with current tech and current TVs it should be all about the games, so does the XB1 have a compelling line up? Yes is the answer for anyone but the most blinkered fanboi
They've never changed before. The 360 had multiple refreshes to get heat down and minimize red rings, the actual processing capabilities were always the same. The only thing that'll change over time is developers getting more knowledgeable of how to push the hardware so they can maximize its full potential. Though this is a little different with both the PS4 and the XB1 since they're x86, which developers already know well from the PC, so games aren't going to get as drastically better looking as they did on the 360 over its lifespan.