Imagine that you are fighting against your enemies and suddenly a monster come from the sky, enormous monster with his minions/youngsters. Then you have to stop attacking your "ex-enemies" and cooperate with them. You don't have to do that though, because you can chose, for example, you can kill your human enemies and escape from the battlefield avoiding the monsters. Just like is the game right now when you lose the match.
That could be aleatory. I mean, not in all matches could happen that. But with a mode which let the possibility to happen it will be interesting a very exciting.
It could be a good mode for Titanfall 2 and it will add a lot of variety to the game, because we are talking of trusting your enemies and react quickly to face the new threat. And if you trust your enemy but your colleagues don't do that? It will be a slaughter.
Oh man, I'd really like that.