I interpreted the second suggestion in light of the first one, which included the point "-any imported py file will be able to choose which version it wants". That's suggesting mixing and matching between versions within the same process space, which is highly unlikely to work correctly (except when modules are specifically designed for that, as indicated by the availability of backported versions on PyPI).
Either way, there's a lot of prior art in this space that actually works pretty well once you're aware of its existence, which means future improvements are likely to come in the form of availability, usability, and discoverability improvements for already popular approaches, rather than introducing radical new concepts.