Don't expect a foveon sensor, the cost of FF would be out of this world, look at the price of the SD1 crop camera. The sensor is very difficult to make, extreme low yield, and lots of other image compromises.
I expect it to be a super low ISO sports camera to best the D3s, not a studio camera. The 50mp 1Ds camera will appear before next summer, and maybe on November 3rd.
5D MK II will match the D800. Canon knows what is coming, and willl have something similar.
Personally, I'd be very interested in a 18mp super low light high ISO camera, and if it is in the $5,000 range, I'd order it on day 1. My 5D MK II is good at low light, bit 1-1/2 - 2 stops better would be amazing.