This is amazing stuff but I have to believe that the multiplayer maps will be smaller, supporting smaller districts or zones - but every structure will be destructible and destruction will bleed into other zones as advertised.
So I'm guessing that the single player and online CO-OP will run in a larger campaign map. There will be no mass destruction even though it's online CO-OP, and that's because each player needs the ability to take the same game offline and still play the same experience. So whether or not another player drops into your single player session, the world you play in only has the kinds of physics that a single XBO can handle per your average game. So we should expect the same kinds of stuff we saw in Crackdown 1 & 2. Of course the graphics and all the rest will be improved since its on XBO, improved physics too.
So I see 3 game modes:
1) Single Player Offline, limited destruction, large map, players can drop in and out any time for CO-OP campaign as with all other Crackdown games.
2) Online CO-OP as described above, same map a single player offline, same campaign, limited destruction
3) Online Multiplayer, modes to be determined at this point I guess, smaller map, mass destruction powered by multiple azure servers equaling about 20x the CPU performance of an XBO. However, I think it likely that as a player on the map, it will be difficult to visually see 20x performance unless you are high up on the map and everyone works together to blow up as much stuff as possible. Even then, your local XBO will have to use LOD to simplify distant objects, so it would seem highly unlikely to be able to see all 20x all at once. That said, I'm sure we will in fact be playing in an environment backed by 20x what a single XBO can put out.