"We know a mirrorless camera from Canon is likely to appear in 2012. What form it takes is anyones guess."
I just reread the post. Unfortunately looking at the G1X I think we'll see a formfactor closer to that camera with interchangable lenses. And the G1X sensor as well.
Oh well, we can dream, right?
There is some sense in what you are saying here. The G1X sensor fits the bill more from the point of view of cost. I have my doubts that Canon would put something into the market in the $2000+ category, which is what a full frame system would probably cost (body plus one lens).
Canon probably needs to have a play closer to $1000 (or below) in order to get the volumes to make a product viable.
Canon also has the problem that due its size as one of the biggest camera manufacturers in the world, it is very difficult to justify niche products. - A niche product would not make any appreciable difference on the Canon balance sheet, and would have to have a very very very strong strategic need to be developed.
Canon's biggest problem, right now, is probably Apple. Loads of people are ignoring P&S cameras because smartphones do an often great job of taking snapshots. (If I look at my wife, for instance, for a night out with the girls, she no longer takes a compact camera with - she takes her iPhone.)
One of the strategies that Canon appears to be following is to educate people more about photography, in order to make them more skilled, and hence more demanding of their equipment. A $2000 product would not benefit this strategy, whereas a $1000 product would (only just) form part of that kind of strategy. I believe the intention of this kind of approach is not to counter smartphones, but to drive demand for more sophisticated camera products in addition to smartphones. The 1X00D and XX0D EOS bodies fit into this strategy as they are now so cheap - a mirrorless system would probably also need to fit into that ballpark.
None of this helps anyone who would like something that follows in the lineage of rangefinder cameras, however.