The fact is, Zombie City was never going to work. It was a monumentally bad idea no matter what the idiot Chase Graves acolytes think. Taking a hard line with the people who provide your food and can nuke you is just dumb. But I guess the myopic violent idiots tend to win just because they're violent and idiots.
At this stage, I see this ending two ways:
1. Seattle gets nuked and everyone dies, which is I think waaaayyy to dark and depressing for this show. Although if Liv and Major get cured and them, Ravi, Peyton, Clive and Dale all get out before it goes then maybe that would be the right balance of tragedy and "happy". Still depressing though. No hope for any of us.
2. They find a synthetic cure for the virus and all the zombies get cured. This one seems like a copout.