If your just gaming and not doing crazy processing programs, i5 is perfect. I however recommend if it's not much more to go with an i7 just for the fact it'll last longer. I won't use future proof bc that term has no meaning in the pc world.
On a side note, games are starting to use more cores like bf4 benefits from the i7 and it's hyperthreads. You'll see more games start to do that now. You could go always upgrade your cpu later too.