If SLI is not an option, and those are the cards you are going for.. No, you will not get smooth frames in BF3 ultra, so change your expectations there.
Secondly, you don't know pricing yet, so I don't see whats the point in waiting. Think of it this way.. You can wait a couple months and get yourself a 560ti (new version) for about $280... oor you can enjoy your games now, get a 570 for about $310, and guess what? when the 560ti(new) comes out, you won't care. You won't say.. damn I could have spent less money to get less performance.
What you will regret, though, is that you spend all that money to get a card, and then realize that you did not buy enough horsepower to run the games you want at the frames you wanted. Then you realize that you could have spent a measly $20 and gotten a more powerful card that would have given you a better experience. You never regret buying a powerful card, but you do regret buying an underpowered card.
Also.. you don't want to wait, but you can if its a big difference.. ??? big difference in what exactly? You are either going to buy the more powerful 570 now or you are going to buy the less powerful 560ti(new). I don't see what the big difference is that you are looking for exactly.