The problem here is (at least) twofold: 1) this is almost certainly a partially arbitrary limitation, since Kaby Lake is architecturally identical to Skylake,

The problem here is (at least) twofold: 1) this is almost certainly a partially arbitrary limitation, since Kaby Lake is architecturally identical to Skylake, yet one is supposedly supported and the other not, and 2) AMD Ryzen hardware has already been sold with the explicit promise by the vendor that it will have Windows 7 support; Microsoft is now breaking that promise. Also, you may be misinformed regarding how Microsoft's support lifecycles work. MAINSTREAM support has ended for Windows 7 -- which means no new features -- but it still receives security patches until 2020. So does Windows 8 and 8.1. In fact, even Windows Vista still receives security patches until April 11th. It seems like what's happening here is that they pushed out a patch that maliciously UN-supports certain hardware. I was running Windows 7 on Kaby Lake fine yesterday and receiving security updates, and now they're telling me I can't. Why? All the chipset drivers are third party and have nothing to do with Windows Update.