As of today, the only camera to support the XQD memory card format is the Nikon D4. And while it is a great camera, no doubt, the single high-end model is not enough to push the demand in the market towards XQD as “the other memory card.”
CFast2.0 is a specification from the CompactFlash Association, which also designates the specification for current CF cards and the newer XQD cards. CFast2.0 specs offer a theoretical performance up to 600MB/s data transfer speeds.
SanDisk is currently sampling new CFast2.0 cards to camera manufacturers to see if they will bite on the new specification in spite of the overwhelming move toward the SD card standard. Medium format camera maker Phase One has already committed to putting the CFast2.0 cards to work in new cameras due to the higher performance over other card formats.