That's a good point. Shell would not announce an EOL date for a specific version. Scripts that used to work 25 years ago, still work just the same. Python scripts that used to work 10 years ago, now need maintenance/porting, no matter how trivial, to make them work with Python 3.

You probably have one operating environment. It is the environment that you wrote that script for. Generalization in 99 out of 100 is introduction of an unnecessary flow that won't ever be executed outside the test but it will eat time.