in promciple yes, but much lower percentages ...
if "old glass" means current Canon mirrorslapper EF lenses ... yes.
if by you mean old manual clunkers, then no. tiny minority of less than 1% fools, who seriously want to use their optically subpar old glass bottle bottoms designed for film on today's hi-rez image sensors. typically those folks also love "retro" cameras with lots of mono-functional wheels, knobs and buttons. and aperture rings on lenses ... la la Fuji-land denizens!
99% are people in their right mind who smartly avoid spending tons of money on freaking expensive f/1.2 crop lenses for use on crop sensors only. they buy FF sensor cameras and FF-capable lenses - either Sony or for lack of FF mirrorless FF systems by Canon or Nikon ... mirrorslapper cameras and EF or F-mount lenses.
in terms of Crop sensor MILC systems, Canon is abolutely on the right track: use a large enough sensor (APS-C, not puny m43 or punier Nikon CX), and keep it small, keep it simple, keep it affordable!
no need whatsoever for expensive, big, fat *fast crop prime lenses*. leave that tiny 55mm f/1.2 niche to Fuji-nerds.
good quality, small, convenient zooms like EF-M 11-22, 18-55, 55-200 plus a few moderately fast, very high optical quality, very small and excelkent value primes like 22/2, 28/2.8 macro are right on track. plus hopefully some day EF-M 85/2.4 STM IS plus maybe a EF-M 50/1.8. bring it on, Canon! forget about 10/2.0, 35/1.4, 55/1.2, 85/1.4 lenses for CROP sensored camera systems, not needed. buy an FF sensored camera and highly affordable f/1.8 to f/2.8 lenses ... much more sensible and way more useful!
a Canon EF/EF-M speedbooster adapter for "old" EF glass and those few, who believe in free optical lunch might sell in reasonable numbers, but not at 500 but rather at 199.