Hate to break it to you, but the xD bodies are not "larger mass market", they are marketed at enthusiasts and professionals, and THAT market is absolutely ready for 4K and wants it. Cameras like the GH4 and BMPC are eagerly awaited and anticipated. Sony has their AX100, and soon they will have a DSLR 4K camera to compete with the GH4. Canon would have to be absolutely insane to do nothing because they WILL lose market share to those products, and because of the way investment is made in glass, that loss will be long term.
I can guarantee that every xD body Canon releases from now on will be 4K capable. So, the only question is when these bodies will arrive. We know that the 7D2 is likely to arrive this year, with possibly another body as well. That will probably be a full frame. There are strong rumours that they are going to release cinema-EOS cameras at NAB that will "steal the show". Do you seriously think that ANY non-4K camera is going to "steal the show"? Really??
Exactly. The question is, when will they arrive? And the answer is, not right now which is all most of us have been saying with the exception of a few.
As far as xD bodies go, there is the 1, 5, 6, and 7. We don't know what Canon's plans are for the refresh cycle of the 6D. The 1D and 5D based on history will definitely not be updated this year. So I can't speak for whether they will include 4k by the time they do decide to release updates which may well be more than a year from now. That, my friend is NOT RIGHT NOW.
That leaves the 7D as the only possibility unless like you are saying, they release another line of xD. Based on the feature sets of the high end cinema line and the current price points, what do you think the 7D or other new xD would have to be priced at in order for Canon to offer it with 4k? So do you believe Canon is willing to cannibilize their cinema line with xD bodies RIGHT NOW?
To your last point about CINEMA EOS "stealing the show" at NAB, that is completely irrelevant as that has nothing to do with xD lines which is what we are talking about here. And no, I don't think Canon could "steal the show" without having at least 4k in their CINEMA EOS announcements at NAB. But again, that has nothing to do with the inclusion of 4k in xD.
Some people in here seem to believe that video is a main driving force of the market for xD cameras. News flash, it is not. They are stills cameras first and poor man's video rig second. 4K to this market as a whole is not significant enough RIGHT NOW.
One last thing. Although the xD lines may not be as mass market relative to the Rebel lines, they are certainly massive compared to anything Panasonic is putting out.