I think it's incredibly naive to say that by 2023 there will be no need to evolve the language in a backward incompatible way, no need to clear cruft from ten y

I think it's incredibly naive to say that by 2023 there will be no need to evolve the language in a backward incompatible way, no need to clear cruft from ten years of continuous development, no need to incorporate new technologies like quantum CPUs or whatever they come up with. History tells otherwise. I bet when they released Python 2 they were not expecting to break the APIs years ahead.