Well I didn't mean they should stop spawning gen 1 like, tomorrow. I meant eventually, like around the time gen 5 or 6 comes out. Obviously right now they are still plenty of people in the middle of working on the mew special research. But eventually, as more and more pokemon enter the spawn pool, you will see less and less of any individual pokemon.

By the way, last time I checked magikarp was still a pokemon that can nest. Every time there is a nest rotation try to check out the local nests near you. Or you can walk magikarp as a buddy, or use rare candy. Hopefully they will soon have a research task that awards ditto, like they said they would.