Why don't you think it'll happen? The game seems to focus on a nice open environment so CO-OP System Link/Xbox Live should be achievable.
I and many other CO-OP gamers will not purchase this game otherwise, so hopefully they'll see sense and allow the Campaign mode to be enjoyed by sociable gamers who enjoy playing games with their mates.
that would be a good idea but i think that you should be able to make your own missions via map editor and play them with your friends online.NOW THAT WOULD BE EPIC