I'll take a stab at this, and I am an EOS-M owner. What difference does it make, if the camera you buy can do the things you want why does it matter if any more are made?
I had a G10 that I wanted to upgrade, I looked at the various options from pretty much everybody, including, obviously, the G1X and the G12/G15. But what won me over to the M was the unique integration with the EOS system I already owned, and that is the M's key feature. If that is a key feature for you then I'd recommend one wholeheartedly, whether they make/import another one or not, if that is not a key feature for you then it is a very competitive market segment and I'd suggest taking some time comparing actual cameras in your hands before committing.
I'd expect the M-III to have the EVF of the G1X MkII, if so I'd really like that, but it doesn't diminish what the current model can do.