Hmmm... Do I want this camera? Probably. If it comes as spec'd, it replaces my 5DII, just as a 1DsIV would. I don't mind the loss of 3 MP at all, and triple the frame rate is a nice bonus.
I don't see it as an amalgamation. The loss of the 1.3x crop factor is a problem, and could only be solved in a merged line by a sensor with enough resolution to allow cropping to a least 16 MP to match the 1D IV (i.e. a 27 MP sensor). An 18 MP FF sensor cropped to 1.3x gives 10.5 MP, a little short of where I'd like. So, really, I see this as a 1Ds IV, whatever they call it. The 'step down' from 21 MP to 18 MP is no biggie, and at least in the P&S line Canon has shown a willingness to drop MP count in a new model.
If the reason for dropping the MP is a new sensor design with better DR and ISO performance, I'm on board.