Peoples were going on about army size. So I'll say this.
Brad said time and again various things about 10,000 vs. 10,000.
Will it be mid game? No. Certainly not early game. It may not even be a common occurence (I can't see 10k armies taking anything less than a lot of resources, and thus if I have 10k soldiers they sure as hell won't all be in one place) but for those truly epic we-are-the-kingdoms-they-are-the-empire-war-is-nao battles...yeah.
ONE THING that I am REALLY interested in (curse you Raven! You have me doing it now!) is the prospect of team battles. Don't get me wrong, I'd love to be the owner of multiple types of forces, but when it comes right down to it, the War of the Last Alliance siege on Barad-dur (hope that's the right name...) was so epic because the elven and human armies combined for it. Not one army under one commander, but two armies.
Age of Wonders did it in a very clunky way. If a battle started and you were RIGHT NEXT to one particpant, you'd join in. Battles were autodone and thus happened in a second, which kinda sucked for team battles. Cities were easier - you could put your units into allied cities (to attack, you'd have to take the center of the city, while the 'outskirts' were free for you, or anyone else, to sit in) which would put you into battles.
Mount and Blade, while a real-time and thus without a whole lot of synergy, did battles over time. So if you were wandering the map, you'd see two teams engaged in battle. You could walk up and join the battle, just walk away, or what have you. I hope that AI battles between AI will at least last for a full turn, if only in SP, so that we players can join in.
Also, I hope that we can put units in the cities of our allies. Perhaps allow us to freely do so when at a certain diplomatic relationship (or as a tech, Benevolent Assistance or Benevolent intents, etc) or when we try to move into a city, give the option to just stay in peace or strike foes down...etc.