Will Canon's FF Mirrorless be EF or EF-M Mount?

NotAPhotog wrote:

One thing I can absolutely guarantee with 100% confidence: they will introduce a new mount. Why? For profits, plain and simple.

That might be the primary reason, but there are other reasons as well.

A new mount would make their new lenses smaller and lighter than their DSLR full frame lenses are. New lenses mean they can refresh their 30 year old DSLR lens designs. And they could add more contacts if they felt they might need them, like Olympus did when they went from 9 contact pins on the Four Thirds lens mount to 11 on the M4/3 lens mount. Thereby making their new lenses future ready.

But you are 100% correct when you say profit is the main motive. Why wouldn't Canon want to sell their users brand new FF MILC lenses, rather than just letting them use FF DSLR lenses they already own?

No camera system that used previously owned or other brand lenses was ever successful.

Where are the Samsung DSLRs that used Pentax lenses, or the Fuji DSLRs that used Nikon lenses? Or the Kodak DSLRs that used both Canon and Nikon lenses? Or those Leica DSLR that used Olympus and Panasonic lenses.

And has anyone noticed that most Four Thirds lenses have lost 80% of their value even though you can still use them with an adapter?

I also noticed that Sony chose to use the E mount for their Full Frame FE system, and not the existing Minolta-Alpha mount. I am certain that many Full Frame Sony DSLR users would have preferred the older mount, but Sony made a smart business decision so they could sell a bunch of very expensive new FE mount lenses.