.. I am of the opinion Apple wanted to release the MBP at WDCC and then launch a new version with Kaby Lake 9-12 months later when Intel released the CPUs, but the Touch Bar wasn't ready so they had to wait until now. Chances are we'll still see a KL update by WDCC 2017.
Unlikely. There are Gen 7 (Kaby Lake) processors that Apple could have bumped the MacBook with now.
http://ark.intel.com/products/family/95543/7th-Generation-Intel-Core-i5-Processors#@Mobile
and didn't. MacBook was just bumped April 2016 and Apple didn't feel the need to bump them just 6 months later. Just as unlikely they will feel the need to bump the MBP 6 months later also. It isn't like the follow on to Kaby Lake is coming very fast in Intel's pipeline. Taking your time presents less risk.
As for the Mac Pro, I honestly wonder just how much better the machine would be with Haswell-E and the AMD W7100/W8100/W9100 (D310/D510/D710) series GPUs. It looks like the main benefit Haswell-E brings is DDR4 memory, but with the drawback that it is reported to draw more power and generate more heat than the Ivy Bridge-E and that might have been an issue for the Mac Pro's power and cooling systems.
Xeon E5 v3 Haswell-EP (won't be using -E) has been superceded by Xeon E5 v4 ( Broadwell-EP). So no good reason they'd be waiting for that. The reported draw more heat is largely bogus system TDP accounting. The v3-v4 systems have integrated power converters. System wise there is not a net increase. It is just that an additional component has been integrated. You have more localized heat in position but overall there is not a net increase. Haswell is hot so Apple can't use it is a old, tired excuse that just won't die. There is not technical basis for it.
Extreme top end GPU there is not much that would help Apple with their given design constraints ( fixed power , custom embedded design , etc. ) . More probable that it is a GPU hold up on the Mac Pro at the moment.
Unfortunately, Skylake doesn't offer an appropriate CPU (the performance workstation CPUs appear to be designed for dual sockets) and Intel has yet to say what Kaby Lake will offer in the workstation space.
No, there is a single socket Skylake-W Basin Falls .... doesn't look like it is coming before 2H17 though ( Skylake-X may Q2 17 , but the workstation line probably is downstream from that. )
https://forums.anandtech.com/thread...-and-skylake-w-processors-in-q2-2017.2475298/