Millennium city is based on the ruins and re-birth of Detroit. I think for an expansion the city of Baltimore would be a perfect candidate for this same sort of concept.

Much like Detroit, Baltimore has a high rate of crime. One of the highest crime rates in the nation (relative to it's population)

I think it would make a good mix of area as well because of how diverse Baltimore city and country are in comparison.

Plus seeing a bunch of NPCs saying "Hon" will be funny.

Everyone who has been to the freeway on the edge of th ezone line knows the upcoming zone is "EXIT"

I expect (and hope) it'll be Vibora Bay. It's part of the Champions Universe, and will make a nice contrast to Millenium City.

Also, there's at least one NPC hero (Amphibian) who is based out of Vibora Bay, so that leads me to believe they are planning to add it.

I'm thinking they're going to be sticking to Champions lore for future expansions. Though, they own the whole IP now, so they can change it if they want.