"I like Python, but keeping both 2 and 3 alive for so long has caused problems that make it hard to justify for serious projects."
Sounds like a strawman arguement to me. People in the community are aware of the different versions of Python and know how to deal with it. This "issue" hasn't affected Google, NASA or the millions of developers/users that utilize Python to the extent that they are in crisis mode. You can run multiple versions of Python on the same system, there are utilities that make this manageable.
What other language is "your" boss going to pick that you can't find issues with? Does he actually understand the technical details and history of said language? You can find all sorts of issues with any programming language, all of them are "Hopper complete."