With the introductions of planes, there's no longer a need for regions to be linked to travel to another land, a la Kanto and Johto in GSC and later HG/SS. Although the same could be said about the larger ships we've had before, planes are a lot faster and easier to commute from location to location with.
Even though the idea of battling on a plane seems completely absurd, I think having the capability to fly on a planen and communicating and battling with other passengers, would be great to finally see happen.
I could see something like this being well utilized for a post game plot in regards to a smaller region being unlocked not too far away. Small enough to where it doesn't entitle its own game, but large enough to own its own airstrip and fill up what is usually a very bland and uneventful post-game.
