Nikon have (fast) phase detect autofocus working with their mirrorless 1-series cameras.
Canon should be aiming to do the same!
Except that Nikon's phase detect AF works only in very good light. Under slightly lower conditions, they have to fall back on contrast AF which completely falls apart for Nikon:
"The J1 and V1's contrast-detection AF systems, which take over when light levels are too low for effective phase-detection AF (and remember that this is the camera's decision, not the photographer's) are less impressive. Focussing is less positive (AF wobbles quickly around the target rather than locking straight on it) but impressively accurate when it gets a 'lock'. The problem is that even in average interior room light, both cameras struggle to find that lock.
I'll rather have fast and accurate contrast AF all the way.
I am surprised no one ever comments on live view contrast AF in the Canon 5D3. It rocks, it really does! Under VERY low light conditions (f/1.4, 1/40 sec, ISO 25,600), it can lock focus while phase detect hunts and hunts and gives up. In good light, it's VERY fast. A serious step-up from previous Canon contrast AF technology.
If the same contrast AF is implemented in Canon's mirrorless cameras, they'll have a winner on their hands.