I think Canon stands on the quality of their lenses and, for DSLR, the quality and consistency of their bodies. There are still those who vastly prefer an optical viewfinder. The pros still seem to want DSLR for sports, but studio is opening up more and more to mirrorless. And look at how quickly the AF in mirrorless is catching up with DSLR. And then the latest hybrid AF of Canon seems to be catching up with mirrorless. It has to be said, Sony are the innovators. Trying new things, taking risks, and proving a lot along the way. Canon still has its quality and reliability and the remaining advantages of DSLR. And again, lenses.
Also consider that Sony lenses are very limiting if you consider anything outside of the kits. You pay, for example, around $1000 for way too many Sony lenses in the mid-range, like the 35/2.8 or the 10-18/f4. The Sony 70-200/f4 is bigger, heavier and more expensive than the Canon 70-200/f4 which still reigns as one of the best lenses anywhere. What was the mirrorless advantage again? An a7 with that huge 70-200 is still heavier and more bulky than my 6D with 70-200. Just one example.
I am about to buy an SL1 I think, with the 10-18mm which I'll get for $250, not $800 like the Sony or Olympus equivalents, or $1,300 for the only ultra wide option from Panasonic (in apsc or 4/3). What was the mirrorless advantage again?
Canon has come out with four really good lenses for the M. Obviously they need to expand that. And obviously they need an M model with built in viewfinder to compete with a6000 and a7XXX in the future. But they still have an opportunity to really do something with M based on their DSLR brand. But they aren't innovating like Sony and risk losing.