We can actually have a mixture of both, infact we can have a race against time to score more points and we can have the AI sit on the expansion that needs to be contested by both factions; ideally their is an abundance of possibilities, I hope the developers are looking into this thread cause we just came up hopefully some good ideas for a co-op mode.
Yeah, it just remains to be seen how much they can accomplish with such a small team. They've shown they've got the guts with SoaSE, but do they have the experience and the time to pull this off? An engine that updates on the fly is serious business.
Oh god yes. a 5v5v5 would be awesome. or any type of 3 teams each other, specially if you can make imprompt alliances (say 5 mins truce in which one side builds up forces in a shadowed area near its 'allies' base only to attack as soon as the 5 min truce is over)
I'd love to play that format. Maybe even to lessen the scale to a 3v3v3 concept. To possibly battle the idea of doubling up, just have more naturally obtained defensive structures or an income handicap that would make players defer from wasting units on a spawn barrage just to find an army twice the size on the other side of the gates.
The more I think about it the more I am liking the idea of a 5v5v5 map. Obivously would require some sort of balance and maybe an objective to achieve instead of the classic team deathmatch thing (like a point in the middle to hold or something) since if one team is raiding the base of the 2nd player then the 3rd team will be raiding that base at the same time so people might be afraid to attack in fear of losing their own base.