I would love to see something even like the new 70D's AF system in the 6D (MKII), but keeping the great sensitivity on the center point.
+1 I agree Dustin. I'm still on the fence, especially now with the 7D Mark II coming. I was just thinking the same thing just the other day: A 6D mark II with Dual Pixel AF and all cross-type, 19-autofocus points.
I'd definitely buy one. I still may get a 6D even when the 7D Mark II becomes available.
As I myself would love to see a more advanced AF system in 6D, I'm afraid that Canon would be afraid of cannibalizing th 5D3 sales. After all, I was also deciding whether to take the leap to 5D3 or just "suffice" with 6D. All boiled down to AF difference and I couldn't simply justify 1500 USD more for better (far better to be honest) AF system. I learnt to live with 6D AF limitations, but I guess there are several customers, who decided to buy 5D3 instead of 6D for that reason alone.
I think Canon created a confusing choice for consumers. You can buy a 6D for less than the new 7D Mark II and IMHO, I think the jury is still out on the question of the 7D Mark II's IQ and noise handling capabilities.
I was doing BIF's with a T3i coupled to a 70-300 4-5.6L and getting better shots than my nephew with his 7D coupled to a 100-400L. Yes, I may have just gotten lucky and there are probably other variables at play, especially camera familiarity. I think the 7D's AF system may have been a bit much for him. My nephew just took a class given by Canon in San Francisco on the 7D's focus system after having the camera for almost 4 years.
As for me, I figure if I can photograph BIF with a camera that has an inferior AF system and is slower (3.7 fps) than the 7D, the 6D for me will be a welcome improvement. I keep scratching my head as to why Canon priced the 6D the way they did
knowing they would introduce a more robust APS-C camera that would compete with it (primarily price and feature set: new sensor, new AF system, etc.), not to mention competition from other camera manufacturers.
Granted, if you don't have the bucks to snap-up a 5D Mark III AND you have invested in a lot of Canon glass, the 6D makes sense. Maybe Canon has adopted Intel's "Tick-Tock" manufacturing cycle model. In my mind, the 6D was a Tick -- the 6D Mark II should be a Tock (we can only hope).