A note to game developers: Just because a franchise is successful doesn't mean that it will survive a substantial change in gameplay like we got with Double Agent. Furthermore, after a bomb like Double Agent it would be wise to return more towards the style that popularized your game in the first place before branching out in new directions.
I'm surprised to see you say this, as I just recently played through the co-op mode on Double Agent for the Wii with a friend of mine, and it was so much fun, we played through the game in 3 marathon sessions.
By the way, if there are any game developers reading this, please Please _PLEASE_ make more games with co-op campaign mode. I've been having trouble finding games like this for the Wii, and these team play games are really a blast.
The solution of this problem is trivial and is left as an exercise for the reader.