Essentially, the whole concept of the mod is that it is set in 2011, one decade before Half-Life 2, one decade after Half-Life 1. Most of the world is anarchic and a wasteland, with the rest being populated by minor survivor states.

i'm interested 

Could be fun, though I would wonder if the Universal Union (CMB) would all be connected to one player (Because the citadels all were connected apparently) or if each would be their own thing but in a combined faction. (Each city having a focus tree?)

I'm just not too sure if I'd want to expect to see xen creature and antlion horde nations. 

I think you may want to bring in the half life 2 beta content. Air Exchange rebellion, anyone?

Could be fun, though I would wonder if the Universal Union (CMB) would all be connected to one player (Because the citadels all were connected apparently) or if each would be their own thing but in a combined faction. (Each city having a focus tree?)

I'm just not too sure if I'd want to expect to see xen creature and antlion horde nations. 

I think you may want to bring in the half life 2 beta content. Air Exchange rebellion, anyone?

I would have each city their own nation with their own focus. I am unsure if they would have an 'overlord' city that has all of them as puppets, but I'd rather not. 
A single beta city is certainly possible, perhaps set in New York.