As fans have noticed/theorized, all of the Fire-type starter Pokémon have been based on animals of the Chinese Zodiac. There are 12 animals
in the Chinese Zodiac. So far, we have six: the Dragon, the Rat, the Rooster, the Monkey, the Pig, and the Dog. We still need six more to complete the set: the Rabbit, the Sheep, the Ox, the Snake, the Horse, and the Tiger. Therefore, I believe that there will be at least six more generations of Pokémon.
I had never heard that theory before now, but that's rather interesting!
Anywho, I agree that the franchise won't end anytime soon. Why would it? It's bringing in lots of money and people of all age groups love it! (Examples: My uncle, 76, has a Pocket Monsters [Pokémon] glass he always drinks out of; my mother, 32, watches Pokémon with me and knows a good chunk of the older Pokémon; college and high school kids play the games; my 4 year old brother knows the Kalos starters and a few others) There's no reason to stop the franchise when it's doing so marvelously!
On my boyfriend, Angel's, trip to Japan (Arceus, I wish we had known each other then, I could have gone too!), he met the creator of Pokémon, Satoshi Tajiri. He was given the chance to speak to him and, while he was never told straight up as to whether there would be new regions (my boyfriend's question was if there was ever going to be a Poison type legendary becase he loves Poison type Pokémon), he said that Satoshi hinted at there being more and also saying something like "going back to their origins" ("The world of Pokémon is vast and beautiful, but just like our world, it always comes back to its origins." -Satoshi Tajiri to Angel) This was a a few years back. And now, here we are, awaiting the
remake of the Ruby and Sapphire games.
I talked to Angel about this about 30 minutes ago when I found this thread and we agreed that the Ruby and Sapphire remakes are most likely tests so that the company doesn't shame themselves by remaking a terrible version of Kanto, their origin.
Even if there are no more regions, which I'm sure there will be, there will always be something to fall back on. More remakes, Pokémon Ranger games for the new regions, Pokémon Stadium, Mystery Dungeon, etc, etc.
I don't think any of this will end anytime soon, and I'm somewhat eager to see what they'll come out with next.