There isn&#x27;t all that much code written for Python 3 to care about backwards compatibility. IMO Python 4 should be:<p>- backwards compatible with the latest release of Python 2<p>- contain all features of Python 3 in some form<p>I think this will result in a very speedy adoption.<p>In the future I propose the following numbering scheme: for any N &gt; M, Python N contains all features of Python M and is backwards compatible with Python M if and only if M divides N.