I think they could sell out single stadium shows in other markets too, not just the ones I named. It's more the south where they'd have trouble. What I think they should do is play a mixture of arenas and stadiums like on the JT Tour - NYC in particular should have stadiums, but somewhere like Tampa or Omaha can only just sell out an arena.
But yeah, the arena show is absolutely AWESOME, and really, the arena setting DOES suit lighting purposes a lot better. Hopefully when they're back in the US, they'll stop this Vertigo x2 nonsense.