The hyperthreading of the i7-6700K is really only worth it if you can use more than 4 cores, which is very rare in games and even some productivity applications. If you do a lot of video rendering or other high-demand work then it would be worth it, but otherwise, not likely. That said, if you play one game in particular almost to the exclusion of all others you may want to see if you can dig up some performance specs running it on various CPUs. For example, back in the Cataclysm Xpack was released for World of Warcraft (there was a graphics engine update in that Xpack) Chris Angelini (here on Tomshardware) did an article which demonstrated that WoW could use all the CPU (and GPU) you could throw at it. That was back in 2010 and WoW has had another graphics update (in terms of how they create some colors and effects) for Legion so it may not be applicable to WoW today.
One possible usage scenario is if you multi-box a game (run more than one copy of it at the same time). Performance can be improved by assuming the affinity of each copy to specific cores, spreading your games out in different cores it can help. Hyperthreading gives you more effective cores and is a benefit. But this only works in that kind of situation and really only if you run 4+ copies of the game at the same time.
I don't expect the gaming environment to change that in the next 3 years; you do want 4 cores, but 4-cores hyperthreaded, not so much.
I'd spend the money on a better graphics card myself, Here's a great option that won't be around long -
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202186
Of course an upgrade will cost more (generally speaking, depends on which cards you're comparing) than $100 extra, but if you actually want to maintain ("maintain" not "reach on occasion") 144 fps then you'll want more horsepower than the GTX 1060 will supply even at 1080p. A GTX 1070 would be a much better option.
You could also save about $20 dropping down to 8GB to help pay for a GTX 1070. You won't see any performance degradation in the vast majority of games and, again, I don't expect that to change in the next 3 years.
Is your monitor G-SYNC capable? Particularly if your video card isn't quite up to maintaining the higher frame rate an adaptable refresh rate will make more difference in the look and feel of your games than the high refresh rate capability (I hate to say that being a fan of high refresh rates myself). Of course if you were to go with that Radeon R9 Fury I linked you would need FreeSync.
All that said, there is nothing wrong with going with a component just because you like it better. Buy the i7 6700 if you just like the idea better and it makes you happy!
And the obligatory - "wait a couple of months". Zen should be here first quarter of 2017, and Kaby Lake as well. Kaby Lake mostly just offers a clock rate bump over Skylake, but will cost the same and more performance for free isn't a bad deal. AMD's Zen is of course an unknown, but you might be able to get a 4-core hyperthreaded version for around the cost of the Core i5 and potentially satisfy that urge to get the hyperthreaded CPU and save money, both. Assuming, of course, that it doesn't give up a significant amount of performance in the games you play.