I registered just to throw out an idea I've had for awhile about these rumors, and this seemed like an appropriate time to lay it down and see what you folks think of it:
Recurring rumor: "3D" camera between 5D and 1D.
Recurring rumor: 1D and 1Ds lines merging
Given the advancements in CPU's over the past several years, there isn't any reason I'm aware of that Canon couldn't produce a Digic V with enough horsepower to produce a 40+ MP camera at 8+ fps with a 1.3x crop mode at 24+ MP and over 10 fps. So a full-size, dual-chip (and/or multi-core) combined 1D/1Ds flagship camera ought to be technically feasible. Let's call this one the 1Ds MkIV. However, marketing might be an issue, but that's been discussed elsewhere.
The "3D" name is problematic, as is often pointed out, but many (myself included) think there's a market for a camera in this slot. Create a grip-less version of the 1Ds body, with the same AF, fully weather-sealed, same FPS (give or take) but lower resolution. (Lower resolution means fewer and/or slower processors = good battery life despite losing the grip.) Call this the 1D MkV and price it slightly below the current 1D price-point. No silly "3D" name, but it fills the market slot for the proposed 3D and the 1D market that isn't covered by the new 1Ds. It also covers the folks that want a full-Pro camera, but don't want the extra size and weight of the current 1D/1Ds-size cameras.
I don't expect any re-shuffling on the 5D's market space, it seems to sit in a pretty good place. If there is a "Video" version, I would expect it to be a fairly minor ergonomic deviation - an "edition" - rather than substantially different hardware.
Full-frame 7D doesn't make sense, but my proposed 1D MkV/"3D" would fit a similar slot.
If Canon has something special cooking, the 1Ds MkIV would be the logical place for it to go, both technologically and from a market standpoint. That is, if the 1Ds IV used a SiOnyx sensor (for example) to give it better image quality that would also better distinguish it from the less-expensive cameras (and might explain the unusually-long delay between updates.) Just my amateur armchair analysis...
TL;DR? "3D" gets called the new 1D MkV and while the 1D/1Ds lines merge as the new 1Ds Mk IV.