It's hard to argue that the Nikons and Canon DSLRs, particularly FF, are still the most power photography tools. Although Leica M9 is my most used and favorable camera, I have admit it's still a nitch.
You want super wide angle? super tele? super fast flying bird capture? perspetive control? best bokeh? yes, you'll always find Nikon and Canon high in the list. Yes, they may not be the very top one, but very close.
All mirrorless, to my observations, are playing the marketing trick to be, more or less, the Leica M clone. Name one that is not! Fuji X? Sony A7x? OK, may be M43 is not.