TL&#x2F;DR: No. Many, <i>many</i> of the changes are backward incompatible with the existing Python 2 syntax and APIs.<p>Any changes that <i>could</i> be made in some compatible way have largely been backported to the Python 2.x versions (the latest stable version of which is Python 2.7.10) that have been released more-or-less in parallel with the 3.x line (search for &#x27;backport&#x27;): <a href="https:&#x2F;&#x2F;hg.python.org&#x2F;cpython&#x2F;raw-file&#x2F;15c95b7d81dc&#x2F;Misc&#x2F;NEWS" rel="nofollow">https:&#x2F;&#x2F;hg.python.org&#x2F;cpython&#x2F;raw-file&#x2F;15c95b7d81dc&#x2F;Misc&#x2F;NEW...</a><p>Enough such has been done that you <i>can</i> write Python code that runs in recent versions of <i>both</i> Python 2 and Python 3 (which is very important for 3rd-party library maintainers that want&#x2F;need to support both it in a single codebase), but to do that you will be forgoing most of the productivity and &#x27;niceness&#x27; benefits of the sort that are described in the OP.