I agree that many 1D-series customers could/should just 'buy a better lens' but the problem is that when you combine the loss of 1.3x crop with loss of f/8 AF, you can no longer even achieve AF at all at equivalent focal lengths that were previously possible. For example, a few months ago I bumped into a guy shooting tiny birds with a 1D IV, 1.4x extender, and an 800mm f/5.6L IS - that's functional AF at a FF equivalent of 1450mm. With the 1D X, the longest possible focal length with AF will be 840mm (600/4 + 1.4x) - that's over 40% shorter, and the extra 2 MP don't come anywhere close to compensating.
From what I see the 1D X will be the best multi purpose 35mm Camera out there ... But (and that is a big BUT) it lacks the specialization of the 1D IV for sports and Wildlife. One could only guess that the next generation of APS-C sensors, which will probably be available in 2012/2013 can fill this gap. The 1.6 crop would then be again on the same level as the MK IV or even better for people who need really long focal ranges (1000mm+).
What I could imagine is kind of a more professional APS-C cam either being the 7d MKII or they introduce something like a 4D which would be a pro body APS-C.
Canon skiped the APS-H line, which makes sense as the 1D MK IV was the only body using this, so it is efficient to drop it, as they could standardize more - especially the low volume pro lines - which is after all the idea behind the 1D X.
Now the rather big question is what will be in the 5d Mk III and I see three options here:
same sensor as 1D X or same as current 5d MKII with updated AF and several other better specs (kind of a 5d II + 1Ds III + 7D mix) or a new sensor in this case a high resolution 24-36 MP one (for Architecture, Stills and Landscape use mainly like current 5d MKII) but still with mediocre AF and several other shortcomings compared to the 1D X. After all they MUST justify the possible 3000-4000$ price gap. Secondly they will/could split that line and do some more APS-C PRO line (4D) ...
So I guess in the next year or two we will see a completely different lineup in the single digit bodies 1D-7D and my own guess is that there will be a Pro APS-C (4D Option)