It all depends how many sell their D700\5D2 to get the latest and greatest. That will see the second hand prices fall (or not!). At the end of last year you were looking at £1400 for a mint second hand 5D2 (admittedly the troubles in Japan inflated prices) and they have been slow to come back down to the £1200 they were previously.
I bought the 1Ds2 with the intention of picking up the 5D2 replacement once it was released, obviously only if it filled my requirements. If it didn't then I was hoping the D800 would be something to look at. I just don't need or want the 36MP though and if the 5D3 is also high MP... sraw is an option but it has to be implemented really well to be worth looking at. As Nikon haven't included it I guess the results might not be up to par?
Ultimately though I am happy with the 1Ds2, the great big clunky old brick that it is. The only things I would like is a faster clearing buffer and better high ISO performance. Higher FPS would be nice as well. A 1DX in a smaller body would be just about right

At the moment though my only option for a more modern body is looking to be a 1Ds3 (still too pricey and now looking to stay that way), or the D700...