Not sure if this has been discussed anywhere before (probably). But how about having new Factions with alternate win conditions on them.
For example you could have a banker one like this;
If your Faction's Influence reaches 150 you WIN the game.
Rogues could be if you control X number of your opponents cards.
Gearsmith could be if you control X amount of Majigs
Arcanist and Warlord i'm not sure about. Warlord screams X amount of soldiers and Arcanist I have no idea unless it's X amount of Coverts. But both are very similar to the Gearsmith/Majigs idea.