There wasn't an expectation that libraries would work nor was there an expectation that the transition should be quick. That's from listening to conversations a

There wasn't an expectation that libraries would work nor was there an expectation that the transition should be quick. That's from listening to conversations at PyCon 2008 and 2009. Back then I got the feeling that this would result in a bumpy ride later on, but accepted it because I was new to Python. It has similarities to how packaging was treated historically. I think this precipitated a number of other problems which meant that by Python 3.3 and 3.4 inertia had set in. There appeared to be a bit of a panic that code wasn't being brought over from Python 2. This resulted in flipflopping on a recommended approach which I would argue was an unnecessary problem. There should have been a deeper assessment of the situation. It was was only in this timeframe that differentiated features started appearing for CPython 3. My experience from the PyCons when CPython 3 was in the early versions was that attention went to possible alternative runtimes. There was a lot of energy going into PyPy, Unladen Swallow, and the like while language features for regular devs were limited. It's only later that a coherent strategy started to form around porting libraries, providing clear and unchanging guidance on migration to Python 3, and big projects committed to migrating. I'm missing a few things, but this combination started to build real momentum. The backend runtime stuff and the limitations of CPython still existed, but Cython and other tools helped ML usage of Python grow. I don't think people who weren't Python fans would have predicted that given the performance constraints.