I honestly think mirrorless is a fad, or at least not a wise investment for Canon.
People really who want the smallest size won't want/care about interchangeable lenses, and people wanting the top quality won't want all the limitations of a mirrorless system. Thus mirrorless stuck in some jack of all trades but master of none middle ground, perhaps useful for some niche of enthusiasts but not something that would sell to most individuals, be it for hobby or profession. You could argue that the Sony A7 is the pinnacle of what everyone has been asking for in mirrorless, and it is very clear in the USA at least its sales are terrible compared to Canon and Nikon's offerings.
I used to feel that way -- that it was all about size -- but I really have come around that mirrorless will be our inevitable future and obsolete all but the highest end of DSLRs someday. That might be 10+ years from now due to the time needed to develop things as robust and responsive as a modern DSLR, but I think it will happen. Here's why:
- They are smaller and lighter. That's a good thing for most shooters, but not all of them.
- No mirror = no mirror slap.
- EVF have all sorts of powerful options to provide large, bright and magnified viewfinder options.
- Mirrorless makes the divide bewtween still and video a blurry and cooperative one. As every photographer will inevitably become a photographer/videographer before too long (I kid), mirrorless is better positioned to support that. Mirrorless can do all sorts of nutty things like capture video all around the time of taking a still, pull the best still from a video in post, etc. Right now, these features (yeah, like on your iPhone) are parlor tricks for photography neophytes, but in time, enthusiasts and pros will find spectacular ways to leverage this functionality to do things DSLRs cannot.
- Once the AF, EVF and shutter tech evolves sufficiently, Mirrorless is presumably far cheaper for manufacturers to make.
And all of this is coming from a guy who loves DSLRs and clings to his optical viewfinder at night. Rest assured that if mirrorless obsoletes anything, it will be to our benefit and not our disadvantage -- or we won't buy them. A high bar of happiness, control and flexibility has been set with DSLRs. Now mirrorless has to clear that bar. Their work is cut out for them, but I am geeked to see what we can do with our cameras when they finally pull it off.
I can add the following to your well-written post: both of my children own 'M's' (stepping up from Canon ELPHs)...and they love them. For years I tried to get them interested in my Rebel or my 40D--no luck. But they love the M+22mm combination; and one, at times, uses the 90 flash in useful ways.
As I've posted on these pages previously, my own 'M' generally has the 11-22mm lens on it. (EDIT: I do not use the supplied Canon strap; I cannibalized the connector and attached it to a Wii-type controller wrist strap...the whole thing fits in the pocket of most of my shorts. The strap also is long enough to fit around my neck.)
The M+11-22mm combination sits quite nicely on a light-and-flimsy (collapses to 12" long) four foot high tripod, a device that I would never trust any regular (I.e. heavier) DSLR to sit on. With the Canon remote, we get family vacation pix that work well in several ways...and all of the necessary gear (including the 270 flash) fits in a very modestly sized shoulder bag.
A post on this thread, I think, sort of got it right: the current M is a good daylight camera (if you accept the slow autofocus). I don't have nearly the expertise that some on this board do, but I have a bit of experience with the 5D MkIII + 35mm2.0 IS lens combo--talk about a light-gathering system!
Mirrorless isn't there yet, but I do wonder what it would take for Canon to put IS on the 22mm 2.0 M lens...and then the inevitable sensor improvement that will come with a future M (M4?!)...and if the auto-focus technology improves as well...
If Canon doesn't see this sort of thing in their future, then, in my view, their competitors will.
The future, for most photography (I think)...is sans mirror, folks. (And I LOVE my 5DMkIII!.)