Switching to python3 is hard, especially if you have a massive python codebase interacting with other systems. Its not as easy as importing unicode_literals. Unicode breaks in very subtle ways.
i wish them all the best, but would've been much more impressed if they'd done it, not simply announced to do it.
No question Python 3 is better than 2, but it's not better enough to justify the move. People will only move when they absolutely have to. That isn't progress, it's inefficiency.