Okay, in that case, I'll play.
What's wrong with the 5D III for your needs? What will these mythical cameras possess that you don't see in Canon's current offerings?
With the 7D update, you'll be getting the tighter pixel pitch, with sharpness-robbing diffraction setting in earlier. Are you willing to put up with the smaller crop-sensor viewfinder, coming from a 1Ds III? Do you need razor-think DOF you're used to will full frame? And although you can add pixels in photomerge, will you still get the perspective you desire? Personally, I love the wide-angle perspective, not just the wider field of view.
If the 40MP-plus monster comes out, as someone noted, will you be willing to pay the price that it will command? I'm assuming you have decent glass, but depending on your needs and your propensity to pixel-peep, will you be happy with sensors that demand perfection from your glass if you're demanding perfection in your images (on the out-of-camera images at pixel level, at least). Also, you're already used to large files, but I would personally be nervous about 40MP+ images and their impact on my storage and processing infrastructure.
As always, I prefer to ask myself, "What does my current gear not offer that I want from an upgrade?" and then see if the new gear really offers what I want. Of course, that requires real cameras to investigate, not rumors.
$.02
