Dont dream too much guys.
6D image quality will not be better 5dmk3. Be it intentionally or what.
The interview with canon product manager at cameralabs.com has already mentioned that they will not let 6D jeopardize 5dm3.
Well, at least we now know with certainly that is not true for jpeg.

We'll see how the 6D RAW files turn out.
The internet is currently rife with rumors the 6D sensor will be the first Canon sensor employing the new 0.18 um wafer process. We'll soon know how true this is.

I'll tap that. Worthy back up body.
GPS is infinitely useful.
I'm more excited about Wifi than GPS. Not that I plan to use Wifi all the time, but it can be very handy when I need a remote and don't have one in hand.