This post in the 5th Gen Poll topic made me think of this.
Obviously Pokemon is going to want to continue for quite some time, as long as people are interested and buy the games. If they simply stop adding new pokemon at some point, at that point things will start to get boring and the games will start to seem like the same thing. Now, of course Nintendo can and will do other things to make the games new and exciting and different, and I look forward to that, but here's where my idea comes in.
How about they don't stop adding new pokemon, but in later generations (I'm talking quite a bit later) they make certain species of pokemon (ones that are less wanted/cared about/used) go extinct?
This I'm sure will get mostly "NO WAY" kinds of comments, but think of the pokemon no one ever cares about or uses. Plus, what they could do is start you off in the game and the Professor will be talking to you as usual. We know how each Professor from each game usually has some kind of thing they specialize in or are studying in particular. This one could be specializing in Pokemon Preservation, and as such it will be your job to save and breed certain endagered Pokemon. You won't be able to save all of them, and as such you will be forced to make choices. Then, each player could have a unique, or relatively unique pokemon environment as people will choose to save different ones.
Now here's the real kicker to my idea which is sure to get people "WTF"-ing. I think that the pokemon that are saved should not be tradeable to another game in which that pokemon went extinct. That way it gives people a truly unique connection with their own game.
Now, a few notes here to clarify certain things (and keep in mind I haven't thought this through too thoroughly, so there's bound to be tons of holes here and there.)
--Not all pokemon would be in the "pool" of pokemon from which to choose to save. I think Legendaries might need to all be fine.
--I'm still not sure how they would move forward after that. They could make it so that the NEXT gen after that uses the player's own data from the last one to create a world wherein the pokemon who went extinct in the previous one don't exist in the present one. Only problem here is that some people may have not played the previous one and so they wouldn't have data with which to move forward. I guess one solution for that is to hit an ol' randomize option and just go with a random world of pokemon.
With all that, I've come to another idea which is WAY less radical and might actually truly happen. (Thinking of things as I type them is interesting to say the least.)
Now, keep in mind that this is for WAY in the future when (/if) there's way way more pokemon, like 1000 or more or something.
Have 1 version of the game instead of 2. And just have each and every person when they start a new file get a random set of obtainable pokemon in their world. This would create WAY more interaction between players, because they'd have to trade much more with people to complete their pokedex. It would also make the game last so much longer in terms of truly completing the game.
Personally as I'm typing this, I see that the second idea is way better, and the first one I think could be used as more of a side-game.
The idea of certain Pokemon going extinct based on your actions does sound like a good idea. (Now if Jigglypuff went extinct, you wouldn't get it in future Smash Bros games - YES!)
And having a random environment with say....about 130 different Pokemon may be more managable than around .... 1954 (a random number I might add) Pokemon in the National Pokedex. Trying to memorise the abilities of of the first 200+ Pokemon is hard enough without Nintendo adding more.
In my opinion, if the number ever did get up that high, the Pokemon world should be set up like the real world (Earth), not just 2 or 3 regions that you can venture through. This would definately make the games more adventurous and you could play for years and make plenty of new discoveries!
I think this would be a great theme for a game or two, but Nintendo wouldn't permanently switch to it, that's for sure. That would kind of change the whole concept of battling through gyms and beating the league to conserving Pokemon: two completely different things. As stated, though, it would make a great side-game.
Perhaps they could give us choices like Growlithe/Arcanine or Vulpix/Nintales, Zangoose or Seviper, and other previously version-exclusive Pokemon. Or you could have to choose between "equivalent" Pokemon like the Pidgey line and the Starly line, so to let you choose between old and new generations.
What you were saying about moving it forward, though, if there were to be two games... I don't think they'd see reason to relate it to the old game at all. They'd just make a new region, some new Pokemon, and you'd start all over again with new choices to make.
Hm... What would they call it, then? The extinction-game, I mean. Pokemon Global Warming, anyone? Pokemon CO2?
I agree with both ideas, actually. There are so many pokemon who are just kinda there...they don't really see any use, and are just collected for pokedex completion. Getting to eliminate some of those would actually make the game more fun. And as for the second idea, that's even better. You'd have to trade with a ton of people for sure, but the pokemon games have always encouraged trading, this would just be a step up.
Maybe they could start making different kinds of games for every new region they introduced. Pokemon Ranger and Mystery Dungeon were new for Generation III, and a good amount of fans were interested in it. The hero of the games had different objective, making the player intrigued to find out more about the game. :x