>>57944385
There's no world in which that doesn't happen because every time a property like this arbitrarily changes its status quo the fanbase always turns on it extremely quickly.
It happened to Yu-Gi-Oh
It happened to Power Rangers
It happened to Digimon
It happened to Final Fantasy
And obviously it happened to Pokemon.
The only way to keep Pokemania going would have been to keep releasing Kanto games with the original 151 mons, but stagnation would have hit that hard and we'd probably be in a much worse place now, assuming the franchise wouldn't have died outright.