I'm gonna stick with my previous comment.
The 5 series will replace the 1Ds range.
Commercially, the pro's have shown they are more than willing to buy 2 5D's over a 1Ds.
It has been the large megapixel camera of choice for a few years now - and i suspect Canon will want to keep that option as well.
I have no doubt it will come with a single Digic 5 and an improved AF. By that i mean maybe 8 full cross hairs and the centre focus point being a new double cross hair. It might even increase the 17 points the 7D has, but the remaining additional points would be a single line focus point.
The Megapixel will be 30+ and the frame rate will pretty much stay the same. Remember, this is a studio, landscape camera.
It may well come with a USB3 connection, or even Thunderbolt - but i suspect USB3. It'll need something like that for the data transfer of those large file sizes.
The weather sealing may be upped a bit and an ability to hold 2 CF cards as per 1DX.
Sadly, i think the price may well be in the Â£2500 bracket, which is an increase on 5D2 opening prices - for many, still a bargain and a price point that would still have pros going out and ordering in pairs...
As for release date - after the 1Dx is actually available to buy but in time for the summer wedding market.
So let's say May! The northern hemisphere has an amazingly large wedding market, and nothing like a new camera to use gets the great pics and referred sales in for new weddings from guests!
Did i mention all those tourists coming to London for the Olympics? Yep - they'll all want a 5D3 for that once in a life time trip!
Next Spring will be a great time to buy a Canon camera