My next body will probably be either a 1DIII or used 1DIIN, the 5D2 was overkill (for me) in the megapixel department, and massively disappointing in the AF/environmental protection department, if it looks like the 1D4 is going to be full frame then I'll probably hold out for that, but the 5DII certainly isn't a 1D slayer!
1D3 and 5D2 are apples and oranges, totally different tools... One is for the photographer who needs high resolution and light weight (landscape photographer), the other is for the photographer who needs speed and performance (sports and event etc). And both have their place in the complete photographer's toolkit.
Well, honestly, the 1d3 is highly versatile and that's part of its appeal. Even if you shot only portraits and landscape with it, you would walk away with some beautiful files.
I think the two can definitely overlap somewhat in the sense that some people using the 1d3 for the purposes the 5d is intended for, will definitely be interested in this new 5d.
The only thing is with the 1.3x factor, you can't get wide enough with the 16-35 or 17-40, and the EF-S lenses do not work. So if you're a landscaper, you'd probably like to have a full frame or crop frame for the UWA.
