I understand your opinion about how the 7d relates to the xxd cameras and xxxd camera... Well the 60D and t3i carry the same sensor, but are not superior sensors to the 7d... the 60D has some goodies that trickled down from the 7d and new innovations such as the much debated swivel screen... The 7d still holds it's own even after nikon upgraded the d300 to the d300s to compete with video, but the 7d has still been dubbed by many people as the d300s killer. The sony is an interesting camera but until production samples come out to really do a side by side comparison in quality and function, it's a bit too early to tell who comes out on top. The 7d compared to the newest 60d and xxd would be like the top of the line mustang whereas the 60d would be the regular mustang with the same engine but less bells and whistles and maybe the t3i would be the same car with manual roll down windows and steel wheels.... It's debatable whether people in the industry consider the 7d as "pro" or not, but canon has made a point to all but say that this is in the same category as the 5d... 5d being a baby 1ds and 7d being a baby 1d.
Theres a difference between the xxD and xxxD models featuring the 7D's sensor awhile after release and those lines featuring a sensor thats superior to the the 7D's, or at least with superior looking specs.
Would releasing the 7D mk2 say 28 months rather than 36 months after the original really make that much difference? The 1D/1Ds lines sticking to a 3 year or longer cycle makes sense given the investment involved on both sides but is the same true for the 7D and 5D? I suspect that the reason the 5D mk2 hasnt been updated sooner is that its linked to the 1D/1Ds.
If Canon sticks to updating the xxD and xxxD every year or so then I'd say a shorter 7D cycle might make sense. Having the pro model outspected doesnt seem a good idea as does having the lower end models only add bells and whistles for 2 cycles while the competision surpasses them.