They are only demoting one of two Windows targets. This isn’t about Windows, it’s about there being no maintainer for one of the two toolchains. Unfortunately, it’s the open-source toolchain that is being demoted.
It's not just one of two. There used to be four Tier 1 Windows targets, and there are still three: i686-pc-windows-msvc, x86_64-pc-windows-gnu, and x86_64-pc-windows-msvc.
