Will use 4 cores and need 4 cores are two different things.
No game maker wants to limit their market by requiring many cores to run.
It is a moot point.
A i3-6300 for a starter can be upgraded to i5 or i7.
Next year, we might see kaby lake which will run on lga1151.
In 4/5 years, the best we have today will be obsolete.
I would, however, buy a motherboard with a Z170 chipset to begin with.
We all have a budget, so trades need to be made.