It’s worth discussing. To be honest, however, I’m not sure how much development burden we would actually save by dropping Windows support. Often, the CI problems that show up on Windows are actually revealing “ticking time bombs” that could easily affect Unix as well—and so they kind of keep us honest about making sure we do the right thing with encodings, availability of OS features, etc. There are other issues that truly do represent Windows-specific quirks, however (such as an inability to share SQLite connection objects across threads, which complicates some tests, and certainly the \\?\ prefix weirdness), but those are fairly few and far between. I also expect that some of these issues will lessen without Python 2 in the mix.
Out of curiosity, did you have a specific set of issues you were thinking of?