Here's my prediction of CPU in the new MBP
Kaby Lake is too new, Although shipped in the spring it was officially released in August of this year.
Comparable performance does not seem much different than Skylake.
I'm betting the 13" will be the 6300 series i5 because of the price and wattage and the 15" will offer the 6600 or 6650 in the i7.
Because these are portable devices and battery life is a key factor the lower watts (and cost) will drive which CPU is offered. Regardless they will be real i5 and i7 products.
Just my predictions.
If past practice counts, it has been my observationApple has never gone for the fastest CPUs and has favored reliability, watts and cost over ultimate speed.
BTW "...when just a few months meant massive upgrades in performance"
The difference in performance between Kaby and Skylake does not appear to be anywhere near "massive." I would bet, depending upon the MB chip set, memory speed, SSD architecture, and other hardware related items the measured speed/performance differences would be negligible.