Canon should bring 2 Models:
• EOS 3 - as small as possible, = like EOS M2, with 70D sensor, fast enough DPAF, some minor improvements, price exactly like SL/100D
• EOS M Pro = "Fuji XT1 killer", 7D 2 sensor, AF speed best in class, EVF, built in flash, built in wifi, GPS and RT commander, fully articulated "retina" LCD, beefier grip to fit LO-E6N battery for 500 shots per charge.
And never mind should those 2 models confuse some consumers. They can still go and buy a rebel or other mirrorslappers.
I am sure Canon will keep the EF-M mount. It' specs are well chosen and the existing lens line-up are all price-weight-size-performance leaders. Add a few more good, small and cheap pancake primes (e.g. 12mm/4.0, 50/1.8, 80mm/2. and a 60/2.8 macro and everythinv will be just wonderful.
I'd love to see a Pro version. There are already some cool looking lenses for the EF-M mount. The 11-22 is quite good. Samyang has a 8mm 2.8 fisheye and a 12mm f/2.0! All of these lenses are tiny yet can produce perfectly acceptable high quality images. We just need an awesome new body for them.
In fact a really good EOS-M3 with a 7D2 sensor would go straight to the top of my "Buy Now" list.