Battlefield 4, Star Wars 1313, Watch Dogs, Call of Duty: Modern Warfare 4, Metal Gear Solid: Ground Zeroes sound like they'll be ready for fall 2013, I'm sure there's a lot of stuff Sony and MS are sitting on and a lot of Direct X11 content coming in general that will be easy to port from PC to 720/PS4.
I don't think content will be much of a problem. Especially for Microsoft, they can just throw around money and grab some exclusives if need be.
I think a next-gen Gears Of War could launch with the XBox 720 next fall. Just a hunch though.