Remember that beyond the hardware, the software really needs to catch up, and it will be a very long time before characters can move believably in an interactive, dynamic scenario.
A Geforce 3 system did FF:SW at 1/10th detail running at like 6 fps years ago. Today, NV35 could probably do it at 30 fps. NV40 probably could do it at 30 fps and 1/4 detail. NV55, which is still technically NV50 generation, could probably do it at full detail in real-time. That's on a PC, and we all know you can do much more with the same hardware on a console. X-box2 is going to have a R500 chip in it, on 65nm silicon, probably something custom similar to the way the x-box is halfway between NV20-NV25. X-box2 and PS3 and Gameshpere will all likely be capable of graphics very close to FF:SW in games.