Read the article. 2to3 is pretty robust, but 3to2 is much less usable. The argument is you need the major library authors to start primarily coding in Python3

Read the article. 2to3 is pretty robust, but 3to2 is much less usable. The argument is you need the major library authors to start primarily coding in Python3 and using 3to2 to backport to Python2. Until this happens, the quality of Python3 libraries will suffer and there will be disincentives to migrate.