Well, the 2.x branch has been rather gracefully backwards compatible for many years. Even the jump from 1.x to 2.x was largely "assisted".

Personally, for me switching to 3 is a massive hindrance and probably I'll never do it. For the kind of things I use Python, the changes are extremely significant and it actually seems to me like a step backwards. It may be an improvement in other respects, though. I don't know.