Pitch: Standard Library Preview Package

Yeah, this is the part that I think needs to be clarified. I don't really understand what fraction of changes in this package are expected to be major, minor and patch changes, and also who the intended audience is. I can see that there are arguments for semantic versioning, permanent 0.x.x versioning, and using it as branch-based dependency, but it's hard to understand the tradeoff in terms of usage/adoption, how frequently it will break or cause dependency chaos, etc. These options are also not mutually exclusive, e.g. I think one option would be to use semantic versioning but recommend using it as a branch-based dependency for some subset of users, which would have the benefit of keeping them on the latest version.