I don't see any more or less 1D Mark IV's for sale or any lowering of the price recently. Where are you looking? It seems that their price is what it has been for quite a while, in the mid $2k's to lower $3k's depending on condition and number of actuations. I doubt that any news of an upcoming 7D replacement would have any impact whatsoever on their price. I would guess that most (I didn't say all) current owners of a 1D4 have at least tried the current 7D at some point and aren't especially interested in exploring that line any further. There are a lot more used 1DX's out there now and a lot more deals on gray market 1DX's, but as canonistic mentioned, the next 1DX may just be around the corner.