So, the question is, if there is an expansion with a MP campaign, what would that be?

To me, a TW MP campaign needs to have 3-4 players max (otherwise turns & games become too long, risk of players dropping out is higher etc) and no AI factions for the humans to beat up on.

So, we need a medieval setting with 3 or 4 factions on a small medium map.

Me? I'm going for English Civil War: Total War (catchy title eh?). Factions are Parliament, King, Scots and Irish (I know that Ireland should be about 5 factions in this period to be totally accurate. Its a popular, well known setting and you have the ability to throw in religion to make a SP campaign more interesting (Anglican, Puritan, Presbetarian, Roman Catholic).

So that's my prediction. I know its not got "invasion" in the title, but I think CA needs to move away from that otherwise they are needlessly restricting their choices for an XP.