I suspect there are many other incompatibilities that exist and Microsoft has just drawn a line in the sand.
Hardware and software don't always evolve in lockstep. Sometimes new hardware arrives that breaks something or it doesn't keep up with the evolution of software. Microsoft has taken somewhat bizarre actions in the past to correct this situation when it happens.
In the 90s just a year after Windows 95 was launched you saw USB, AGP, UDMA, PCI and other hardware advances come to market. Windows 95 supported none of it. They released Windows 95 OSR2 to OEMs to add support for all the new hardware. Windows 98 was a long way out and they needed to take action to support new hardware or face being displaced in the market.
With all of the hardware advances of the late 90s and the rapid decline of the 16bit CPU, ISA, and a lot of other legacy systems, Microsoft wanted to make a clean break in the 00s. Windows XP wasn't going to support any of the old cruft of the 80s and early 90s. The problem was that in the years leading up to XP, OEMs refused to start shipping PCs that met the minimum requirements. They were still shipping with legacy hardware that wasn't compatible. So Microsoft stopped shipping Windows 98 and instead replaced it with the crap fest known as Windows ME. WinME was a rebranded Win98 with one key difference, it had all of the "legacy" drivers removed giving it the same minimum specs as WinXP. Unfortunately some of that legacy was so ingrained that WinME was incredibly unstable.
The main issue is processor errata and architectural oddities that need to be fixed in the kernel itself, such as problematic (buggy) instructions or unexpected behavior in the scheduler (e.g. moving execution from core to hyperthreaded core), deep sleep states. If those bugs aren't fixed, users might experience random freezes/reboots or even being unable to boot.
[1] https://downloadcenter.intel.com/download/25476/Windows-7-US...
If they are built for Windows 10 and use Windows 10 kernel-mode APIs, they won't work on Windows 7.
However, I don't think Intel won't build drivers for Windows 7. It's against their own interest. Intel just wants to sell hardware.
Porting/using as reference Linux drivers (a lot of which are written by Intel people anyway) to Windows just doesn't seem to happen very often. Technical difficulty aside, which is significant (I've written both Windows and Unix (although not Linux) kernel mode drivers for years), nobody seems to care about such things, so I wouldn't get my hopes up.
With the added benefit of being able to run on immutable disk images or to roll them back to safe states in case some malware decides to take residence.
There are already problems with Skylake where you'll do a fresh install of Windows 7 and none of your USB ports or network devices will work because they require newer drivers. Microsoft is doing their best to drive everyone to Windows 10 by not doing another service pack or releasing updated ISOs.
Microsoft is the one not doing the supporting. Which means that if something doesn't work, and you create an issue with them (think enterprise customers) their official response is going to be that you need to upgrade. This is perfectly reasonable and Apple does this all the time. There is no reason why older iDevices can't install newer IOS, besides pushing people to upgrade.
I don't see Windows 7 "not working" with Kaby Lake. Maybe things that require deeper OS support, like Optane as DDR chips, or booting off Optane. Maybe Thunderbolt 3 won't work right. But for the most part, most things will work just fine.
Think of it this way, if OSes had to actively support new chipsets, you would need to buy/get new install disks with every release. That just doesn't happen.
“Windows 7 was designed nearly 10 years ago before any x86/x64 SOCs existed. For Windows 7 to run on any modern silicon, device drivers and firmware need to emulate Windows 7’s expectations for interrupt processing, bus support, and power states, which is challenging for WiFi, graphics, security, and more. As partners make customizations to legacy device drivers, services, and firmware settings, customers are likely to see regressions with Windows 7 ongoing servicing.”
There might also be hot new important and/or whizz-bang features on new silicon that Windows 7 does not support and Microsoft doesn't want to support on 7.
Probably means there won't be any for < Win10