Believe it or not, you don't even have to change your workflow to try out python 3. If you're on a Red Hat/Ubuntu-based system just add a '3' to everything (python3, pip3, pdb3, etc)
I've been bitten by Poe's Law[1], despite the winky. Blast!
Edit: Really though, it's a problem of apathy. I'm supposed to care about python 3? Why? When I type "python" on the command line (and everyone else that doesn't care, which is most every "filthy casual", right?), I--and everyone else with a default install of Ubuntu and CentOS/RedHat--gets python 2. Fix that, and overnight you'll have massive python 3 uptake.
In fact, you're suggesting I set myself up to be stuck with the problem Maven is in, which is that everyone has an "m2" repository even though they're onto Maven 3. I'm supposed to hardcode "3" into everything? C'mon.
edit: added relevant platforms