What we know about Sun Valley so far

Sun Valley is rumored to be a major UI code overhaul expected to land in Windows 10 Pro Product Key—the build that will drop in the second half of 2021. To be clear, the "rumored" part means exactly what it says—so far, it's rumors only, with multiple sources but no confirmation from Microsoft.

WindowsCentral's Zac Bowden published a piece on Sun Valley in October, with information mysteriously attributed to "sources." ZDNet's Mary Jo Foley followed up to say that her unnamed contacts confirmed that the project exists—and she has seen engineering references to a "Windows 10++" due next fall—but Microsoft's official response was a rather cold lack of confirmation:It's not new for Microsoft to deliver some Windows features through cumulative updates. We have nothing further to share.