We should decide on Python 2.7 support and announce it with the next release. Numpy will drop it for new features at the end of 2018:
https://docs.scipy.org/doc/numpy/neps/dropping-python2.7-proposal.html
I think we discussed this before but I couldn't find discussions. I think going in approximate lockstep with numpy makes sense, so we could make 0.20 the last Python 2.7 release, or 0.21. Our release cycle has been about a year recently (blame me if you want), so 0.21 is probably a bit away.