What cpu would be a good investment for unreal engine 4 and other next gen appli

I am in the midde of building a rig right now. The question I have is what CPU would be a good investment for being able to run next-gen titles such as The Witcher 3, and Fortnight and things like that. I don't really want to drop a bunch of cash right now and not be able to max things later. For example, right now I plan on getting a 3770k, which I realize is the end of its generation, but anyway I would hate to get that and then all of a sudden next-gen games start needing 6 cores or even 8 cores to max out and have good fps. This is my first non-prebuilt setup so go easy on me if its a dumb thing to worry about.

Here's everything else though.

HAF-X
GTX 680 Classified
G.Skill 16gb 1866
Noctua DH-14
Samsung 840 Pro 256GB SSD
Corsair 1200W PSU

And like i said I'm not completely sold on which motherboard/CPU to get because I want to buy it and keep it for a long time but still be able to handle things like unreal engine 4 and whathaveyou. Also, I realize not much is known about this engine yet but I just thought I would try my luck and ask anyway. Thank you for your help and sorry if I'm not asking this in the right spot.