I think this is rather unlike the Python 3 situation. My guess for the resistance to Python 3 adoption is that it was, by design, not backwards-compatible with Python 2. C++ versions are not completely backwards-compatible, but I think they are more than the Python 2 to 3 switch. What is certain is that lots of other languages release new versions a few times a decade. See, for example, version histories of:
https://en.wikipedia.org/wiki/Java_version_history
https://en.wikipedia.org/wiki/C_Sharp_(programming_language)...
https://en.wikipedia.org/wiki/ANSI_C