What packages will stop supporting 2.7 Don't panic, ArcMap will still be using it... at least for 10.7
Numpy/Scipy drops support of python 2.7 Dec 31, 2018 get your code ready
Guido speaks 2020 is the big end The BDFL, Guido speaks at PyCon 2016 about python 2.7
Announcement Overview — Python 3.7.0a0 documentation yes... 3.7 is on its way
Announcement What’s New In Python 3.6 — Python 3.6.0b2 documentation final release candidate
iPad and iThings Python 3.5 comes to iThings don't get further behind...
Additional The key differences between python 2 and 3
Some frivolity ... but some resources
do check the resources section.
also, here Coming to Python.... preparation and anticipation
Dan:
Do you know if there is an esri end of support for python 2.7 occurring in 2020?
esri will have to limp along in ArcMap if they keep that strain beyond 2020. They actually don't support 2.7 directly, but python 2.7 isn't being supported with updates, security patches etc, so if something arises in python, then everyone is on their own.