I read that and it gave me 5 seconds of hope. But then "The only way that annotations take on meaning is when they are interpreted by third-party libraries" a

I read that and it gave me 5 seconds of hope. But then "The only way that annotations take on meaning is when they are interpreted by third-party libraries" and "Following from point 2, this PEP makes no attempt to introduce any kind of standard semantics, even for the built-in types. This work will be left to third-party libraries" means the author really isn't serious about it. If you don't have a standard semantic you've got nothing useful.