I think the Defenders will be fine. There are enough 20-somethings living in the area that enjoy hanging out in the GA section and building the beer snake to keep the team going. Plus they built a decent following over the last couple of years and Audi Field is maybe the nicest sporting venue in the area to watch a game/match. I plan to go to at least a couple of games next season.
And no matter what happens with the Commanders, Audi Field will be filled with FDS chants for years to come.