I just caught myself thinking about a way of making battle scenarios more interesting. As we all know, a scenario comes to an end if any force does not see an enemy for a certain time - but I think that on some occasions it may be fun to have to go looking for him for a bit, instead of just getting the "Nobody home" sign. So maybe a type of temporal limit could be set in which an enemy should show up over the horizon in some cases, preferably non-campaign battle games? That way, you get a bit more realism and can develop your forces for the impending battle, instead of just going into the fray from the start. I am aware that this is not very practical in many multiplayer games, but it could be useful on special occasions.
Which brings me to Nr. 2: short, operational campaigns that take maybe a few days. This kind of thing could be interesting for a multiplayer environment as well. I know this one has come up a few times already, but it is just so attractive...