I can't imagine them realistically staying in the tower too much longer, simply cause of all the damage. They'd have to spend a lot of time fixing a lot of the holes in the walls made by the pipe bombs, not to mention all the fire damage. And if they try to, I can see a huge feud or another "war" coming about between Micheal and Burt or someone else. Plus they've exposed a lot of weak spots in the security, and the fact that there's an intelligent zombie running around punching in codes and talking.
They need something much more sturdy, possibly something underground maybe that can't be touched from above. But then again, you go underground you corner yourself with no way out. They also can't go higher in the tower cause all it would take is a few more fires to completely destroy the entire building and everyone inside it.
They do need to move and soon. The Mallers still know where they are at and they are all out of sweat jars to call in reinforcements if they came and attacked again. I could see the base being an option but I think too much time would be needed to fix some of the openings.
I don't see how staying where they are any longer is survivable. Both the mallers and the zoms know their location, and the place is a wreck.
No idea where to go from there, though.
What about a total wiping out of the non-front-and-center characters. And then separated groups fighting in different places for a little while before they come back together at ground 0 and find out it's all a trueman show type thing and everything is fine.
But seriously. I expect a mass killing of sorts, and the end of the tower.