Every new pokémon generation brings 100-150 new pokémon, with gen vi being the exception having only 70. If they keep doing that, we will hit the 1000th pokémon during generation 8 or 9.

That's crazy, and I wonder what will happen then. Will Game Freak take a half-decade break from the series, or end it entirely? Since they're independant of Nintendo, Pokémon is sort of their only source of income. I don't know what choice they'd have but to either keep making Pokémon games until the series is slowly run into the ground, or allow themselves to be bought by Nintendo and respectfully retire the franchise.

Also, I know everyone else has more or less said the same thing, but I don't know what pokémon number 1000 would even be, considering they've done God already.

I'm assuming pokémon number 1000 will be the last in line to the batch of mons of that generation, or course.