Why is it so necessary for you to make claims about something that doesn't even exist right now?
You keep claiming that 5970 would be twice as fast as GTX295. Obviously you make this assumption based on performance of a single 5870. But when it comes to pricing you are also very quick to claim it yourself that 5970 is not exactly equal to two 5870, but a bit lower. Then how the hell is it supposed to be twice as fast as a GTX295 when a single 5870 isn't as fast as a GTX295? As good as crossfire scaling might be, it cannot give more than 100%.
As far as your theory about dual GPU cards being sold for less than the cost of individual cards is concerned, that is totally wrong. Both AMD and Nvidia charge premium for such products.
As far as prices are concerned, currently the lowest price of 5870 and 5850 on newegg is 400 and 300 dollars. Don't start with supply issues. If those problems of shortage exist for 5870, than obviously those problems are going to exist for 5970 as well.