I find this a bit unlikely, but it was also mentioned we’ll see a second EOS-M camera announced in the fall, probably not before Photokina though. It would be the “pro” model. I’m confident one is coming, I’m just not sure it’s coming that soon.Pro model? Then it better be full frame.
Have you seen EOS M bayonet/mount ? Its just too small to fit FF in.
You would need new (bigger) mount with new lenses for such camera. No way you can directly attach EF lenses to such body without adapter. You need to increase flange distance to DSLR like.
But APS-C sensor is quiet a win compared to other brands. Pro model with bigger body, PASM dial and EVF (could be attachable) could be a good seller. Such body with 22 f/2 pancake and some sort of wide angle lens (something like 11 or 10 mm, for shooting buildings etc) could be a nice travel setup when you dont want to lug around DSLR.