This is great news & confirms what I'd already suspected. We've all seen the surveys over the last few years asking what photographers want in their next DSLR. Pretty much after the 50D came out, many more people started ticking the "high ISO performance" rather than the "more MP" box. Canon seems to have listened. The "more fps" crowd is also fairly vocal, & Canon seems to be using fps as their competitive advantage point against Nikon (& others). Also, very high resolution CMOS sensors are not so great for video.
I particularly appreciate the tidbit on the new teleconverters. The line is "if you're an APS-H shooter & like the extended reach of that format, well, the new teleconverters are better than the old ones & will give you back the reach you gave up by switching to FF, and the 1Dx will AF as well or better with an f/4 lens as the old ones did with f/2.8 glass". Unfortunately, the marketing department doesn't really seem to be conveying this particular message, and the no-more-f/8-AF issue doesn't help either (e.g. the 2x TC becomes useless on anything but f/2.8 or faster glass).
The 1Dx, then, is a calculated risk for Canon. They are betting that they'll make more money from the faithful that move up to a very high IQ 12/14fps FF body that costs $2500 more than the 1DIV (plus the few working at f/8 that will upgrade their lenses so that they still have supported AF, & those that buy TCs for the reach), and that the higher unit volume of the now single-model 1D line will drive costs down over time & keep them competitive for years. In this crazy economy, they'll have to get as much mileage out of the 1Dx as they did with the 1DsIII (and the 5DII, which continues to sell like hotcakes 3 years after its introduction).
Can't afford it & need the fps? Well, then I guess the 7D's your camera, but at least the 7D's there. I'll go so far as to say that the 7D (& certainly the 7D II) is a calculated part of their APS-h phase-out strategy in the 1-series. If they incorporate the mirror & processing developments of the 1Dx in the 7D II then we're looking at a mighty fine sportsman's crop camera in 2013.
It's a similar gamble on the resolution side of the house for the traditional 1Ds customer: "we're giving you 18 very high quality gapless megapixels & a completely redesigned metering system rather than 25+ MP". They've obviously figured that the few pros that they loose to Nikon (or medium format) will cost them less than maintaining a two-model 1D lineup.
Personally, I think it's the right decision. I'll add another reason that hasn't gotten a lot of airtime in the discussions revolving around the 1Dx:
Pretty much anything but the best L lenses would be massively outresolved by a ~30MP FF sensor, especially in the corners where higher resolution APS-c (& even APS-h to a lesser degree) sensors don't have to worry about it. They're well aware that wide-angles are their weak spot & have updated several of them to compensate, but at 30MP anything with less resolution than five-star-rated L glass just wouldn't cut the mustard. Such a camera would expose every single flaw in their aging lens lineup that they use as a major marketing point for its breadth & versatility (which unfortunately also makes it harder to maintain over time). We'd just continue to see more & more reviews like this one
A very high IQ 18 MP FF camera has the opposite effect. That's the same pixel density as a 7mp APS-C sensor. Not much to worry about there; if a lens looked fine on a 1DsII then it should look fine on this (& the same assurance cannot be made for the same lens on the 1DsIII and 5DII).
Unfortunately that leaves me with even less hope that we'll ever see lenses like a 28mm f/1.8 USM II, but lenses are a lot harder to predict than bodies so who knows...