I live in a similar project (old WWII airfield), that has the same approach to walkability - but it is only viable because one development agency owns rights to development and ensures there is a strong mix of housing types and utilities - its not perfect, but it is a lot better than say old tenement blocks in industrial towns - my local fish and chip shop in Lancaster was the same faceless tenement house, just that someone had converted their living room into a chip shop. It was the only amenity for 20 minutes. Horrible place.
Anyway, wandered off track a bit - it is possible to build a whole town (2000 homes) with one commercial super-contractor. However it is bumping into local democracy issues already so anything bigger is always going to need a proper mayor. Like a real city.
We ended up with an overall controlling agent, but then a wide variety of developers built various parts of the development. So there's a fairly nice selection of home styles, and builders, from one-room condos to 6500 sq ft super homes.
Utilities are controlled, we get our internet from Verizon (FiOS), trash, etc. but with the controlling agent as the broker and bundle negotiator.
There's a semi-elected board that runs the place, I think 7 of 12 are developer people and the rest are elected from the neighborhood. The condos each have their own controlling boards.
AS the neighborhood gets more and more developed, the developer will be ceding more and more slots from the board to elected officials.
I don't know if there are any plans for a mayor, but I think we'll end up with around 15-20k residents once everything is complete.