There's some hope, as they've already got the "player-specific" quest victory thing going:
https://forums.elementalgame.com/329219
3. The mechanics in Elemental are a bit different than the typical 4X game because even in terms of warfare, there are very different paths. For instance, Player A may have a huge army ready to steamroll but Player B may have an incredibly powerful sovereign who can wipe out vast armies and Player C may have built up an incredible well of mana that can be used to decimate vast swaths of the world and all three of these things could come together at once based on which path players take and of course all 3 could lose to Player D who wins through the quest victory condition if they're not careful.
http://pc.ign.com/articles/926/926924p1.html
While this is a strategy game, it will have a storyline. You'll play as a hero character that has an epic quest to accomplish (think of something along the lines of having to throw the One Ring into Mount Doom); the completion of this epic quest can win the game. However, there are other heroes who have epic quests of their own to complete. You know the quest status of the other heroes, and they know your status, so it's a race to completion.
Not quite secret victory conditions, but that is a good idea. For balance purposes It might have to be an on/off game-config option that turns off the part of your screen that tells you about the quest progress of other players. I imagine the devs cringe every time they hear the words "make it an option", but I don't think that one would be an overly massive headache.
Oh, andas far as not spewing ideas at this point, remember that they did ask for it