From what I know, World of Warcraft does something like that on a conceptual level. Obviously syncing game state in non-action game like WoW is probably a little easier than something like a full blown action FPS.
Planetside 2 is a great and current example of multiple massive 100+ player battles occurring simultaneously in the same server/map.
Obviously its graphical detail is nowhere what was shown here, but the precedent exists, and the only thing that would be different is the geomotry and texture res.
Obviously its graphical detail is nowhere what was shown here, but the precedent exists, and the only thing that would be different is the geomotry and texture res.