Who says there is a 5DMkIII? I think this downward revision of pricing has nothing to do with 5DMkIII. Anyway, 5DMkII is good enough for most people. So if FF is what you are looking for. Then this is a good time to buy. Deals like these sometimes only happen once. Nobody knows for now if these pricing are going to sustain. So just do it.
If there really is a 5DMkIII round the corner, Canon is releasing cameras like coconuts falling off trees. I will seriously think twice about upgrading. I mean if a new camera body comes out with every update instead of major upgrade, face lift, technological advances, new building material, etc. Then what is the point of changing to a newer model?