Python standard library can of course be improved with such a model, but the cost overwrite the beneficit by a large margin.
First this proposition is not backward compatible. Basically it will break any script using such library for the first time if internet is not available.
Second, the distribution of standard lib with python is a solved problem. New solution will bring new "bugs" in particular on debian at least which has its own way to distribute python and if such feature is intriduced will create incompatibility with other kinds of python. The current "bug" I'm thinking of is that by default debian don't ship tkinter, breaking any installation instruction given by a software developper.
Third, the python stdlib is a really strength of python and even if it has some limitation, it does the job good enough for a big number of case. To my knowledge, the only significant weakness of the stdlib is that requests does a far better job than urllib, but urllib already make a very good job and is definitely usable.
Fourth it is a jump in the unknown of which consequences will probably when it will be too late to go back and as such should be taken very carefully.
Fifth, as far as I understand the core reason of the initial talk is that twisted will support forever python 2, and as such demand that the whole python ecosystem find workaround to allow this attitude. Breaking compatibility with python 2 was a failure but now we must live with. If I understand correctly the path chosen is helping as much as possible migration, force developper to migrate if they want either new features or security uodates and let python 2 users with no suported solution if they want to stick with python 2. As such asking that the future of python is drive by keeping the python 2 compatibility forever just go against all the effort to cope with python 2 python 3 transition and will basically will be a burden forever for the whole python ecosystem evolution. In my reading pretty all the talk is as weak, but my mail is already very lonh