as per https://www.scala-lang.org/2019/12/18/road-to-scala-3.html , it's going to be a while before the standard library becomes open again for additions and binary-incompatible changes

what shall we do with the PRs at https://github.com/scala/scala/milestone/78 ? (nearly all of them are library PRs, not compiler PRs)

I'm tentatively thinking we should close all of them; linking to this issue in a comment; but leaving them on the 2.14.0-M1 milestone, so we can find them for possible resurrection someday