I'd expect another update to the D1 series body rather than a complete new camera: the body itself is a fine design, and the revisions made for the D1x/h got rid of virtually all the complaints about the original D1.
In terms of spec, I'd expect a higher resolution in the 8-10 MPixel range and a higher frame rate to challenge Canon's EOS-1D. We might well see two cameras again: a direct challenger for the 1D with a 4-5 MPixel resolution and an 8 fps frame rate - aimed at the photojournalist market, and an 8-10 MPixel version with a lower frame rate - for the rest of us.
When? Well the D1x/h have been around for just over a year now, so I wouldn't expect to see the new camera(s) before 2003. Cost? The D1x actually came out at a slightly lower price than the D1 when it was announced, so I'd hope that trend will continue.