Numerous large projects and companies have publicly stated that they are stuck on Python 2 and it's easier to migrate languages, even to ones that they have to invent (Go) than to migrate to python 3. At least one of these companies had Guido on their staffs for years. Another, also with Guido on the staff, needed over three years to migrate from 2 to 3. The overwhelming body of evidence shows that migrating a large project from 2 to 3 borders on impossible, but there's always someone willing to pop up on HN to say how easy it is.