Py3k offers almost no immediate advantages compared to Python 2.x -> that slows down an adaptation rate -> long term advantages are eaten by a burden of supporting two incompatible language versions -> by the time Python 3.0 gains sufficient momentum it will be already obsolete.
The Zen of Python is violated: practicality is bitten by purity.
The Zen of Python is violated: practicality is bitten by purity.