Thats exactly what I was thinking regarding the 5870 and why I waited for the 2gb version, but as it turns out its just not something to go for. The extra gigabyte of ram doesnt do anything for performance in 3x1 eyefinity mode as 1gb ram is sufficient already, except for in very few games. Games in the future will require more vram but then the gpu itself will struggle anyway so I dont consider that.
The price on it is almost the same as a 5970, and thats not taking into consideration active display port adapter (I think I would need a total of 3 of them).

5890 would be really nice to have, but I dont know when its going to be released.