No it cannot, the 670 is 14% average faster than the 7970 on multiple benchmarks on Toms Hardware:
http://www.tomshardware.com/reviews/geforce-gtx-670-review,3200-15.html
Now, lets run Hitman Absolution for a decent example, settings on Ultra with 4x MSAA and at 1440x900 (far from 1080p mind you), Vsync on:
That isn't very good performance at all, and would be unplayable at a higher resolution. You claimed that the 'high end' cards can max everything, well they can't. Same goes for Assassin's Creed 3, everything maxed at 900p and the framerates get very choppy in the cities. Now the 670/7950/680/7970 may all provide good performance in Battlefield 3 and a few other huge titles (60+ fps Ultra 2560x1440 etc) but overall they won't max everything at 1080p, far from it. That's where the 690/7990 step in, they can max everything in any game out at a high resolution and keep the frames from dropping below 50. That is high end. The 670/7950/680/7970 can max about 80% of the games out there at 1080p but won't get amazing framerates, probably average 30-40 in more recent games on Ultra. In quite a few of them they'll drop from 100 to 30 in some areas which for a lot make the game unplayable or at least an annoying experience. Making them mid range. The 7850/660ti/580 performance range wouldn't stand a chance at maxing any of the games this year besides DmC, they'd suffer greatly in the huge titles like Battlefield 3 & Crysis 2. Making them low end.