@CyberPanel said:
But I think there are 1000s of project still using 2.7.5 (serious projects). So it is not very easy to retire 2.7.5 like that.
I am working on python 3, but it may take time, as I am already faced with some issues.
Understandable. That said, just several years ago, many of the most significant Python packages in existence which are on this list were red, and now over 90% (nearly all) are now green, meaning they are ready. In fact, there are millions of Python projects (applications and packages) in the world today and many of them are ready. I am not trying to scare but to inspire you by showing that a large portion of them have underseen preparations some time ago:
https://python3wos.appspot.com/