I think a scene with all those figures look impressive but how practical would it be in terms of gameplay mechanics and realism? Are you going to have your hero hack and slash through thousands of enemies at a time?
God of War got busy at times (and that was on Easy level
). But they had a couple of cut scenes, obviously not real time, where they're fighting Barbarians or whatever.
Infantry battles fought without air support is mostly about attrition. Greater numbers (assuming comparable tactics) usually wins. So how are you going to have one guy cut through all those enemies?
Or you could make half of them one side, half another. But you can't control more than one guy at a time and the rest, you'd have to depend on the AI. That's not much fun.
But it would be a visually impressive feat to render that many figures with high detail in real time. Just not sure what kind of a game you can make out of that feat.