That's an old wives tale that is getting older by the day. People like to roll that excuse out not to move to Python 3 and it may have been true in the past but there are now enough libraries available to get most stuff done in Python3. It is true that the laggards are starting to look like the are living in the past. Python3 was released 3.5 years ago and is getting a real head of steam. Projects that don't move over will eventually get replaced entirely by projects that have either moved to, or been created onl for, Python3. This old "the libraries aren't available for Python3" story is a legacy story too and just sounds like an excuse.
Even in 1.5, Django's Python 3 support will be "experimental". This, quite simply, takes Python 3 off the table for the foreseeable future.
The major Linux distributions (Ubuntu, Fedora) aren't aiming for full Python 3 support until 2014 which. The core Python team themselves aren't expecting Python 3 usage to take off until 2014 either.
In real-world usage, we can't all just drop all the libraries we're using and switch over to another because "it's new".
Exactly my point. Projects that don't make the transition risk being perceived as legacy and irrelevant. There is real opportunity here for new solutions that embrace the new rather than stoically stay in the old.
Can you provide a single solid reason to upgrade to Python 3 beyond "it's new"? In the real world, the advantages of using Python 3 must outweigh the negatives before I can justify upgrading our systems to it. Currently, all I can see is a minimum of 1 year of downtime while I either:
1) Wait for Django 1.5, and deal with all the bugs resulting from the upgrade, or
2) Move our entire code base out of Django into something else, and deal with all the bugs from, effectively, moving to an untested system.
