I think that one of the advantages to making some kind of balance fix mod would be that we don't in fact know what changes CA will be making to multiplayer game balance in the expansion - they could in fact just think that it's good enough and concentrate on the single player.

If there is a community supported balance fix, this could well end up being adopted by CA, providing there is sufficient support - as this would minimise any work they need to do. So basically I think that working on a balance mod would be a good thing - it would provide a fix to those of us who want it, and quite possibly influence CA for the expansion.