While this is looking a bit far ahead, I'd like to state this.
An article stated (too lazy to link, check 3DS thread) that the 3DS carts have 2GB of storage. This storage capacity means it can contain every single Generations I-V game (even duplicates) with tons of room to spare, even if all 3 Gen V games max out the DS to 256 MB games. If dupes are removed from the calculations, then potentially SIX TO SEVEN GENERATIONS OF POKEMON COULD BE STORED ON A SINGLE CART, REGIONS, GYMS, NPCS, EVERYTHING.
I see significantly larger regions, and the ability to visit other regions a lot more commonly coming up in future games.