You might not be able to get any flagships, but you'll probably be able to get next gen hardware that is as fast if not faster than current top of the line cards. The RV530 for example, 12 pipes @ 600MHz and updated feature support could give you the processing power in the X800XL/6800GT range, give or take depending upon efficiency. And being a midrange part I'd expect it to be priced in a range from $199-249.
Ofcourse then there'd be the 7800 series, we might see some GTs or vanilla 7800s that might go AGP, and I don't really know anything about nVidia's midrage parts.
Then I'm not sure about the flavors of the R520. Again I wouldn't expect the flagships on AGP, at least not anytime soon, but there will be next gen cards on AGP thats for sure.