Canon issues a new model when they change the sensor size. The 7D is certainly not going to change, its a very popular camera.
Not sure I understand your point on that. True, there is no precedent for changing a sensor size between models in a particular series, but since they only make three sizes of sensor, I don't see any history that would definitely preclude it. I'm not saying you're wrong, just not sure I see why you're right.
I usually waffle and end up skipping every second iteration of a camera (went from a 20D to a 40D, for example), but one thing that would *definitely* make me jump directly from 7D to 7D MarkII almost immediately would be a larger sensor. It certainly makes no sense to expect the 7D to jump to full frame, but for a camera that Canon clearly wants to sell for a higher price point than a Rebel or 60D, an APS-H sensor would make the 7DMarkII a much easier sell to me and, I'm sure, many, many others.
Here's a blog post I put up over a year ago: http://progenyoflight.blogspot.com/2009/08/prognostication-from-dark-and-smelly.html
I was wrong about a LOT in that post. I don't follow the rumor mill religiously and had not heard rumors of 1D Mark V being full frame, but considering that rumor, combined with the idea of 7D MarkII going APS-H, maybe I was right about a few things, just two years early.