I expect that Nintendo introduce new contents in pokemon via DLC, in pokemon Sun and Moon.
What I've looked at some posts was the insatisfation with pokemon series cause the "same role story", "the evil team chasing the legendaries", "the gym after gym pathway". I don't think Nintendo will change the formula of Pokemon series (like they almost did at Pokemon Colosseum/XD) or do the MMORPG (like they promised to do with Zelda WiiU). They could add new contents once a month or periodically; a new pokemon, a new ability for and old' mon, new region or island or even a new side-story!
Everytime you beat the pokemon league there are some contents, like the Battle Tower, frontier, or Delta Episode. But those are minors and with a couple hours you can finish it. After that, you get stuck with breeding, shiny hunt, battle spot. The metagame will always have the same threats, the same pokemon roles. It gets predictable (Yes, IT DOES, the rank S and A of any metagame will be the almost the same until the next generation).
Now imagine this situation: You are like at 6th Gym and then (POW!) nintendo introduces a new pokemon to be found in the wild and no one was knowing it. The expected reaction from most players is: stop the common story and let's hunt that new pokemon! I would do that, of course. Then the smogon community will start to discuss the potential roles of this new pokemon, to OU? to VGC? to UU? defensive, offense? Mixed? Nintendo then, would accomplish what they wanted: using the same pokemon formula, but taking it attention because of the introduction of new contents (the introduction of Volcanion, Hoopa and Diance are examples of this). Now, imagine the potential with a new city, or a new side-story? It would make the game more versatile, flexible. Not the same tedious path.
Of course, I'm not taking account if all this will have a price. Nintendo could estipulate a price the new region dlc, with a couple dollars. 0,99$ for the new pokemon? I don't know. Or even this is possible (laughs). Otherwise, I would be very happy. It will make the game more playable in a lively mood.