Pokemon is like dynasty warriors. It's literally the same game every sequel there is, but they both have a strong, loyal, cult following, and they will tell you that the new Porsche 911 is 2 inches longer than the previous model and that it has slightly more down force, but we a know it's the same shit, just a different toilet.
People that have been playing for 20 years aren't about to stop yet. They show their kids, kids show their friends, the cycle continues, and Porsche continues to release the same 911 every year, dynasty warriors releases the same game next year, and pokemon will continue to exist for 30 years at least.