So after the quests you do in Skyrim theres always a "u might be called back to help" statement for examples..

Nocturnal says you might be summoned to defend the twilight thing again...also after the civil war , at least on Ulfrics side he says you might be called on again...i think those would be two good parts of skyrim that could be added to with simple patches or DLCs.. also not sure what is up with the Thalmor? They talk about them alot as if there a problem were they in Oblivion? Thats another thing i think they could add a battle with them.. but just some thoughts..whats everyone else think??