Except there was an alpha. There were people like me who PLAYED the alpha on very high end hardware and spent a decent amount of time on the alpha forums discussing performance to get an idea how different cards were performing.
Yes, there will be driver updates to improve performance, but this game is running on an established engine... if you expect a miracle, you'll probably be disappointed.
I was getting 40-45fps average maxed 1080p on a single 1200/1800 MHz 7970, which is around twice as powerful as a 560ti (which is a low-midrange card now....) . You do the math. If you can handle fps dips into the 20s it may be playable maxed out for you @ 16x9, I guess...