I think victory conditions can even be pulled away from triggers. The conquest condition is handled (quite inefficient for the moment) in EndGameManager. But as I think the number of victory conditions should be quite limited. These can all be implemented as separate cases.
What I want to ask. If you select f.e. the wonder condition, and you're the first to build a wonder, that means the game ended and you've won. But what if you kill all your enemies before you make a wonder? Do you still need to go the boring way and build a wonder?
The same for the other conditions.