"At 1080p, a gtx 1080ti is going to cause CPU bottlenecks in some games, no matter what CPU is used."
That's what you said, I just corrected you. There is absolutely no way a gpu can cause a bottleneck on a cpu. I don't care if it's a i7-7700k pushing a gtx 720, the gpu is not bottlenecking the cpu, the cpu will still perform at its rated speed and IPC. The gpu only bottlenecks stuff that's actually downstream, in this case the monitor, since the monitor will only receive a fraction of the info being processed by the cpu. The gpu is the bottleneck. Reversed with a pentium pushing a 1080ti, the cpu is the bottleneck as the amount of info to the gpu is severely curtailed. But it's all flow from source to monitor, it doesn't go backwards gpu can't bottleneck a cpu, only hdd, ram, lan etc can.
And no, game coding being harder on the cpu than gpu is not a bottleneck unless the coding is beyond the ability of the cpu and slows it down, as in the case of i5's in some games when you turn on things like hairworks, which really require 4c/8t cpus or better to run. Hairworks is highly cpu/thread intensive and will bog down a lesser able cpu, driving it easily to 100% loads, creating the bottleneck, because then the gpu is shorted of info. Downstream. Even with uber high settings driving the gpu to 99%-100%, that's not bottlenecking the cpu, it's still working at its rated speeds and IPC, it is not slowed at all, it's not bottlenecked in the slightest.
Get it now?
And to answer the op's question again.
Absolutely yes, a i7-7700k can bottleneck a gtx1080ti at 1080p, the game Ashes of the Singularity being a good example, you can expect fps in the 20-30 fps range if you use too many cpu dependent settings, but that particular game is miserably optimized, requires a minimum of 4c/8t to run decently and really doesn't get much better than decent even with 1080ti sli.