It looks like Microsoft is keeping to their word and actively blocking Windows update on system that have new CPUs. Apparently if you are on a system with a Intel “Kaby Lake” processor or and AMD Ryzen processor when you check for updates you’ll get this message.
Both Kaby Lake and Ryzen processors and all new processors from both AMD and Intel moving forward will only be supported in Windows 10. Windows 7 has ended its mainstream support such as functionality improvements since January 2015. Even though Windows 8.1 is still in mainstream support, Microsoft has choose to discontinue support for new processors.