Well I feel the word "ultimate" throws a bit of the impossible into the vote game, today's "ultimate" is generally tomorrow's also ran.
But, when Canon (note "when") develop & bring to Market a 1D body, 50MP Sensor, 8 fps, built in WiFi, +65 focus points etc etc, I'm on board in a New York second, hopefully that 50 MP sensor will have all the attributes of the current Sony 50 MP sensor.
Considering the 645z has most of these points, but lacks some, and sells for $8,500 I'de hazard a guess that Canon may bring this Body to Market at the 8k to 10k point, which would work very well for me, I can flick the 5DMK III which other than the focus system I feel hasn't been much of an upgrade over the 5DMK II, completely bin my 1Ds MK III & coupled with the 1Dx II (not a lot wrong with the 1Dx, but the 1Dx II has to be better, right ??), then I'm in the happy happy camper group.
For a year or two at least, but still waiting for that "ultimate" camera, which is a bit like that Unicorn of Nuero's, or the well hung squirrel of Sporgon's, don't see too many.