Maybe I'm weird (Ok, I KNOW I'm weird, but that's beside the point), but I just don't have any serious desire for a mirrorless camera. They're ok for what they are, and I don't begrudge anyone that does want one, I just personally don't find the trade off worth it. If the M2 or whatever it's eventually called has all the 70D goodies like everyone hopes, and falls to the sub-$400 level, I'll probably pick one up for times I REALLY don't want to drag a DSLR along, and as an emergency back-up-to-my-back-up body. And that's due to mirrorlesses current, singular, advantage... size. Unless it's for a use case where size is the absolute top priority, I don't see the draw. But hey, to each his own.
What would it take to change my
Full Frame: Currently slim pickings, and very expensive
Good AF: The best mirrorless AF is almost up to yesteryears Rebel, but maybe some day
EVF: No lag, no visible pixels, and galmut as good as the best human eyes (and doesn't need to be calibrated). That one will be a while.
And last but not least...
Antigravity: Because that's the only way you'll be able to handhold all day with a mirrorless, lenses which are quite hand-holdable with a gripped or pro body. Even something relatively dainty like a 100-400 would be unbalanced and awkward on a mirrorless. Unless you think it would be humorous to see people with a 70-200/2.8IS II on a gimbal head shooting a wedding... actually, that probably would be humorous for most of us