The advantage of mirrorless and the main selling point and attraction is the smaller body AND lenses.
Canon’s M-series problem are their lenses, you simply have to use the EOS-system, which is fine as the adaptor works like native, I mean they holds the patent and blueprint and code so it should work like the adaptor isn’t there. This does not however solve the lens problem, I think there are more bodies released in the M-series now than there actual lenses. In the a similar span of time Fuji have managed to put out mk2 of their 23/33/56 mm primes. You can clearly see where Canon’s intentions are with the M-series, it is that they are not serious about it for the people coming from DSLR. The whole range is designed for people who used to look into compact but now mirrorless. In that regard, all they really want are a couple of entry level zooms, they will never put a 400L on it, I don’t think they even know you can do that. The young YouTuber start ups wanting a flip up screen, Canon branding, smaller and good at focusing. It takes all the boxes. The whole “full frame” is probably meaningless to them until may be they own the camera and then into photography for a while.
The angle of the M-series as a back up camera for the bag is a VERY niche market, first you got to have a bag of Canon glass, and then in the position to even need a back up camera, not a back up, but like back up of a back up…perhaps 4th down the list. I actually considered one of these when it first came out because it is small but in the end I end up keeping a last gen 5D3 body as the 3rd camera over a M-series. The 5D3, being a few years old is still vastly superior. However that isn’t fair to the M-series but the point is, I would be looking at it from a perspective of a DSLR which is unfair as clearly the marketing and target audience is for someone who is getting into photography, not already into photography. Now my 3rd body is an A7III, I kinda wish it is made by Canon as that should have been the plan but at least somebody is doing it. (This is the bit DSLR Canon user wants but this isn’t what Canon is doing)
Fuji’s strategy on the other hand is the one that is targeting at photographers who has DSLR kit already, or already big into their cameras, hence the rangefinder-esq X-Pro, the retro styling, the DSLR like of the X-T. They know what photographers are after and they give it to them in spades. The M-series is not for that crowd.
Sony A6500 is an interesting one, there is 1 major downside to that, there is no flip up/side screen. I think Casey Neistat used to shoot on Canon 80D due to the lip out screen, then he went to the Sony A6500 for a while but the lack of flip out screen drove him nuts as he can’t see whether he is in focus and he can’t see his framing. The images on it was almost indistinguishable to his normal Sony Full frame set up. This is why iJustine vlogs with a Sony RX100V on the go, it has flip up screen. (I think her studio set up is a Sony A7S2 with an external monitor). A LOT of vloggers start out videoing with a Canon GX7 for this reason, once they get past using their phone. At this price point the most attractive feature for a lot of customers are video, and shooting yourself in the face
, it is a massive thing at the moment that’s why it is baffling Canon took so long to implement 4K, and baffling how they didn’t implement Dual Pixel into 4k for the M50. Besides all the cropped factor when shooting 4k, it becomes a 2.4x crop. Keep doing things half arsed.
At this point I’ve lost track where this entire thing is going! Right….The M-series is where is because it is designed to be there. It will be a few years before it is something to go up against the A7/9 range, or something comes out to do that. When it does, it will play catch up because that’s the nature of technology, you start late, you play catch up. Canon can do it, I look forward their flagship full frame mirrorless when it arrives.
It's not for me though, give me compact and light every time 
