[popo]

A mirrorless camera with EF mount seems really very stupid. The achievable size advantages would all be gone. The "empty deep hole" serves no purpose. An adapter solution would be "good enough" for keeping EF compatibility really. If they really chose EF for their mirrorless camera it will hurt them on the long term. 

 

Pentax tried to do that with the K-01 if you remember that one. It failed miserably.

I think the last statement should simply be Pentax failed miserably. I don't think that is a useful example to say a DSLR-mount mirrorless would fail, since their actual DSLRs aren't selling either outside the few units to remaining system users.

 

The one feature that would sell me a new body is better AF tracking. DSLRs are far from perfect, and I'm not convinced mirrorless have caught up. Videos I've seen showing how mirrorless is as good as DSLRs are simplistic and not challenging scenarios e.g. predictable, large targets. I think using image data processing techniques could eventually allow mirrorless to surpass DSLRs but we're not there yet. Combined with longer lenses, body size is far from my list of priorities.