Bottleneck wouldn't be the right term to use actually but I can understand where you're going with that nomenclature. I would say that you should first try it out and see if you're getting favorable frame rates. At best you may have to tweak each title's settings in game and find what works for you, i.e I'm assuming you're going to be gaming on the system/laptop and not productivity duties.
Yea, it would suck to spend money on a gpu just to have it work at 50% wile the cpu is maxed out. I was always told higher resolutions kinda lessen the gap, so i plan on getting a 3440 by 1440 curved ultrawide, and i hear the 1070 ti is good at those resolutions. I just dont want to waste money if the cpu only lets the gpu run at 1060 levels.