I guess it depends on your standards. Me, I'm fine with 30FPS. The 570 will handle BF3 just fine at 2560x1600. Just bump down anti-aliasing, leave everything else near maxed, see how you like it. That is how I play it.
Adding the second 570 would allow you to play it maxed out, but the answer to your question is yes, the 570 will run it.