While alternate victory conditions are not something we usually see in TW games, you may see something similiar to Kingdoms. Where if you unite this country and this country you get this unit, or if you units this little area this guild opens up for you. Perhaps even something like Barbarian Invasion where if you set up this, this and that, then this faction comes to age.

While I don't think they'd change actual victory conditions (I mean the control provinces thing has been there for a while now.) You may see some additional bonuses if you do certain things as related to history.