I'd be interested in an M with a built-in EVF. A camera with an awkward hot-shoe EVF just doesn't cut-it with someone who uses a lot of fill flash.
To me, that sounds like bigger. In the case of the M, I don't think bigger is better.
Mirrorless APS-C with EVF could be built only slightly larger/heavier than current EOS-M.
I am not in the least interested in any low-end Canon "M". If Canon wants me to ever buy an "EOS-M", they need to build it
* very compact = not much bigger than current EOS-M
* very capable = IQ, AF, EVF, handling, performance, battery life 500+, Wifi + GPS + Speedlite RT radio controller on-board, fully articulated LCD, fully weather-sealed]
* very reasonably priced = about 200 Euro less than an equally capable SLR [because it is so a hell of a lot cheaper to manufacture; less parts, less mechanical crap, less calibration issues]
Basically, I would buy a full 7D equivalent with 70D sensor+live-view-AF and touchscreen for max. € 1,200