These rumored specs seems too good to be true for $2700 (like others have said), considering that things like AF is the same as the 1Dx (more then twice the price) and pretty high frame rate.
And speaking of frame rate, the 1Dx uses 2 Digic 5+ processors. At 12 fps at 18MP= 216MP/sec. Scaling that to a 22 MP sensor, Dual Digic 5+ would be able to move 22MP at nearly 10fts.
One Digic 5+ would maybe do 5fts at 22MP??
So unless the 5d mk3/mkx has dual Digic 5+, I don't see how it can do 6.9fps.
On a single Digic 5+ CPU I can believe anything roughly under 5fps
I am assuming that the 12fps the 1Dx does is limited by data throughput, but the limitation could be mechanical (mirror movement), in which case the upper limit of throughput is below 12fps at 18MP, otherwise Canon would have used just one in the 1Dx.