Lexar has announced that they'll be producing XQD cards (only used by the Nikon D4 at the moment) later this year. The strangeness to this is that the original co-developers of XQD were Nikon, Sony, and SanDisk. SanDisk so far has declined to make a XQD card, which has raised eyebrows.
On the other hand, we have only one low-volume camera at the moment that supports them, so it simply may be not wanting to be ahead of the market. In that sense, it's a bit like Apple's very early adoption of Thunderbolt. For accessory makers, it's installed base that really interests them, and it will take some more cameras with XQD to build a useful base.
That raises the question as to what those future cameras might be. D600? Not likely. D400 (replacement to the D300s)? Maybe, although that would also imply something about the D400 target being even more pro than it currently is. Canon? Not likely that they'd roll XQD in lower end models when they didn't in their just released high-end models. That really leaves Pentax and Sony.
Sony, of course, was first to put out an XQD card. It seems unlikely that they'd do that solely for a D4 from Nikon. Indeed, if a Nikon D4 was going to be the only camera to use XQD for the first year or two, I'd have thought Nikon would just OEM a card under their own name. Thus, it seems logical that we'll see at least one Sony DSLR with an XQD slot in the coming year. The Nikon D4 gave Sony the chance to iron out any wrinkles in their cards and reader before committing their cameras to them. Indeed, being used in a D4 is a sort of endorsement, as it's basically top-of-the-line and it really shows off the XQD card performance.
Consider a different scenario: Sony launched XQD with one of their own cameras and no other cameras used it. We'd be getting the "it's Memory Stick all over again" comments on the Internet. XQD is not Memory Stick by any stretch of the imagination. XQD has some real long term benefits for cameras needing write speed. Benefits that CompactFlash and Secure Digital can't match under their current definitions.
But SanDisk, curiously, has been silent.