The GTX495, when it does come out, will be a dual GPU card and, I would think, pretty difficult to beat. But lets wait until any of these actually materialize before making comparisons. So far, no release dates for any of these next generation cards have been officially confirmed. I can't imagine, with a GTX480 already in my rig, that I will need to upgrade until the next next generation comes out.
Oh dear ambam, a bit of a daft assumtion i'm not saying your gonna be right just like notty22 says lets wait until they all hit the shelves.. At the end of the day i'm only jealous cos I bought a 5970 about 2 months ago and it looks like these cards will kick my 5970's ass.