No gamer will accept Intel graphics for gaming. Maybe card and such games but you seem to want more.
HOWEVER there are two other questions to explore.
1. Is it future proof?
No. Look to the past to see that nothing can be absolutely future proof as the future is unknown. All it takes is a bug that isn't known or a patch or revision and the chip or part is cast aside.
2. Maybe you want to ask if this CPU will drive GPUs today and for a little longer.
Now that is easier to answer. The i5-2500 was noted to hold up driving 3 GPUs years ago (passage to follow) so hit GPUBOSS (see google) to compare your i3 with the i5-2500.
"Our tests demonstrate fairly little difference between a $225 LGA 1155 Core i5-2500K and a $1000 LGA 2011 Core i7-3960X, even when three-way graphics card configurations are involved. It turns out that memory bandwidth and PCIe throughput don't hold back the performance of existing Sandy Bridge-based machines. "
How many years will it continue to work well with the current generation of graphics before it becomes old?
Will it be compatible with Direct X 12 games and other games that require multiple physical cores?
I am on a tight budget and asking if buying an i3 6100 in the 1st or 2nd quarter of 2016 is a good or bad idea?