Intel is telling its partners that Kaby Lake will be a better overclocker than previous generations and that this architecture will introduce two overclocking enhancements: BCLK aware V/F curve and AVX negative ratio offset.
The BCLK aware V/F curve promises to help you to achieve higher clock stability, it's an adaptive voltage mode that work with BCLK. Next is the AVX negative ratio offset, this feature gives you greater control over Intel Turbo Boot Technology to achieve better overclocking stability.
Kaby Lake will be Intel's third generation on the 14nm process, it's a further improvement of the Skylake architecture so it won't be a big leap forward. There will be some new features here and there like the two overclocking options mentioned above, and overall you can expect a bit more performance at the same thermal envelope.