I still see Canon's path as pretty obvious and easy.
I'm bookmarking this so I can quote you in 2013 :-)
Please do. I'm, offering a money-back guarantee if I'm wrong.
Nicely fills out the line, giving consumers and pros more choices and helps transition buyer to two bodies each.
But why would Canon want to split the former two bodies (40d/5d) into *five* different ones (70d/7d2/6d/5d3/5dhd)? Sure this gives people more choices, but Canon is about making money and this variety also creates confusion and more support and manufacturing costs.
Imho if they expand the ff line they'll drop one of the crop cameras, i.e. no 7d2 but a bumped up 70d. And your "5d hd" might be very well an expensive "1d hd" at first because the people really wanting a $3000 36mp sensor have switched to Nikon by now.
I'm sure every manufacturer would produce just one model of anything if they could be confident it would sell and if they had no competition. But, they do have competition and if Canon doesn't meet the market demand, others will.
It is clear from the Rebel line that using modern manufacturing techniques, it's possible to offer minor differentiation and still keep the line profitable.
Consumers like choices. Ever go shopping for a TV, a car or even laundry detergent? I don't know about others, but if I'm spending $1,000 or more on a product I'm going to make sure I've compared every available model and picked the one that I think will work for me. If one manufacturer doesn't offer any choice, I'll go to the one that does offer some choice.
If having three (maybe four) full frame options and five or so APS-C options is beyond someone's brainpower, they probably aren't shopping for a DSLR anyway.
We've been through this discussion before on numerous threads. Both the 60D and the 7D have been great sellers for Canon. A full frame equivalent of the 60/70D is more of a threat to the 5DIII than to the next generation of the 7D.
7D owners have a high level of satisfaction and are fiercely loyal to the camera. Having just developed that market, it's unlikely that Canon is going to abandon it now.
A 6D is never going to satisfy most 7D owners, who want the extra reach , build quality and professional features that the 7D offers. And, despite the fantasizing that is going on, both the 6D and the D600 are going to be positioned well below the D800 and the 5DIII.
I'm the least confident in the high-megapixel camera. Not sure what the market is for that. But, I assume Nikon did some market research and they seem to be selling, so I imagine Canon is not going to concede that customer base and if they can slide a high megapixel sensor into the existing 5DIII body without major modifications, it's a financial winner for them.
All fun to speculate about. Good news is that after this week we'll know what Nikon is offering and that will give us a very good idea what the 6D will be like.