I mean if what they want is a better standard, so there can be a dozen compliant operating systems we can all compile our stuff for, then maybe.

To look at things from another angle, what if having had POSIX all these years actually made things more uniform, in the sense that we didn't have variance between systems as large as e.g. between a BSD Unix and a Lisp machine? What if that were our choices today. As it is the largest mainstream departure is maybe Windows.

None of the things mentioned are POSIX _or_ portable.