No it will not bottleneck the 6700K. just overclock it and you will be fine. To check it install rivatuner and display on screen display to monitoring to check the cpu usage during gaming and of course turn off vsync. If cpu usage remains close or a bit more than 90-95% then it will bottleneck. If so then max out the graphics and it might help you to reduce bottleneck.
But I think it will not bottleneck 1080ti by any means. Specially when overclocked, not a chance.
You don't need a i7 7700k. It will not be a note worthy improvement. Stick to your cpu for now and upgrade after few years as per requirement.