It might sound easy but that would be a critical component of such a rewrite. Python's standard library is implemented using the same API so much of that would

It might sound easy but that would be a critical component of such a rewrite. Python's standard library is implemented using the same API so much of that would need to be rewritten. You then have the risk of introducing bugs, etc. This post is doing something similar. They're rewriting the internal implementation through progressive refactoring and will then look into more long term incompatible changes that can be wrapped in a translation layer. These projects are difficult as a lot of python code exists in the world and a minor change in behavior can have large unintended consequences due to Hyrum's law.