Generation II

vaporeon era is over long ago, i left with many good eevee, and you can now find them in 5km eggs too

We don't know yet how and when it's gonna happen... but you can save Pokémon with good IV that have an evolution on Gen II (like Eevees, Seadras, Golbats, Scythers, Onixes, etc...).

I think Niantic need to upgrade our bag too, because only 250 slots for Pokémon won't be enough on Gen II.

I wouldn't start saving up eevees until legendaries come out since they have to come out before gen. 2. Enjoy the game now and evolve those eevees because you may get bored holding your breath forever!!!!!!