Even an overclocked 6600k will bottleneck a 1070 in some games.
Unfortunately there are just some games that will absolutely hog your CPU. The main two I know of that max out my 6600k @ 4.6ghz right now are The Witcher 3 and Total War: Warhammer.
Both will rack up to 100% usage in certain situations (in towns/cities in W3 and large battles in TW:W), and cap my GPUs usage at well below max.
So the answer to your question is; yes.
But by how much? That really depends on the games you play. For GTA:V and Call of Duty - which are both years old by now - you shouldn't have a problem, but just remember that you will come across a bottleneck situation eventually over the next couple of years.
So, you should be fine with what you want to do. BUT I still dont recommend it. AMD's Ryzen CPU line is set to launch in a couple of weeks, with pre-orders already topping sales charts on Amazon.
AMD are significantly under-cutting Intel and offering substantial performance gains for the lower price tags. Intel will be forced to respond with price cuts, so it would be silly to pull the trigger on an Intel CPU now instead of waiting a month and seeing how the market is.
Either you end up with a cheaper 6500, a better intel CPU for the same price of the 6500 now, or a much better deal with an AMD CPU.