They're still making 5D2 and selling at around $2400. If this "new high end" is announced at $2500, it will instantly kill the sales of 5D2 that they still have to clear the stock of.
If they are still making 5DII and expect to continue selling it after this new end camera is announced, it would suggest the following:
More expensive than the 5DII - If it would be at a similar price, it would instantly kill sales of the 5D as you say....no matter whether it is named 5D3 or not.
Not named 5DII or 5DX Canon will reveal a 5D3 at some point - but they will not be selling it alongside the 5DII - in fact, just announcing a 5D3 will kill sales of the 5DII, simply because it will create the impression that the 5DII is "obsolete".
So, again, IF they are still making 5DII and plan to do so for a while, it would actually make sense to have a February announcement of a $4000 "3D" (or whatever - just not a 5D3), and then a $3000 5D3 late in the year.
I'm expecting £2500 to 2700 for the 5D3. And I really don't think even Canon would dare make the market wait until "late in the year" for that camera.
They may still keep the 5D2 available when the 5D3 is out, but it'll be far cheaper; about half the price of the 5D3. Right now, the 5D2 is about £1500 - close to half the price I'm expecting its successor to hit the shelves at.
I suppose also, how low can they go with the price of the 5D2 and still make a worthwhile profit from it? I really don't know. But I won't buy one.
Canon 5D3 , 70-200mm f/2.8 L IS II , 24-105mm f/4 L IS , 50mm f/1.4 , 85mm f/1.8 , EF 2x III , Samyang 50mm T/1.3
Canon EOS M3 , EF-M 18-55 f/3.5-6.3 , EVF-DC1
Olympus OM2-SP , 50mm f/1.2 , 55mm f/1.2 , 50mm f/1.4 Silvernose , 135mm f/2.8 , 28mm f/2.8