It's all speculation really, here is my view based on previous new release timelines and rumours.
I don't think Canon is going to combine the 1Ds and 1D just yet. Having separate studio and sport cameras makes sense. I would guess that Canon will release a new 1Ds MKIII in Feb 2007 and the 1D MKIII in Sept 2007.
If you need a camera now then get the 1D MKIIn, it's a superb camera and will be capable of producing great images for many years to come. Just take a look at the original 1D, it is 5 years old, only has 4MP but photos from it are still stunning.
If you hang around for the next model then you're looking at an approx 10month wait and it (1DMKIII) will probably launch at around £3k, which is around £800 more than the current MKIIn model.