We plan to drop support for Python 2.7, 3.4, and 3.5 for typing-extensions.  These Python versions have reached end-of-life for at least a year and tooling starts to be a problem. The Python 2 version of the library already has some omissions compared to the Python 3 version. Older versions (up to 126.96.36.199) will remain available for these Python versions.
We also plan to drop the typing backport for Python 2.7 and 3.4.  This is what later became the typing module in Python proper. The Python 2 module had its last commit in 2019 and the Python 3 module was made obsolete with the introduction of typing in Python 3.5. Of course, old packages will remain available, but we will make no new releases.
If you have any concerns, please voice them either here or in the linked GitHub issues.