It’s 2018. I feel it would be best to be pushing python3 as the preferred version. I understand avoiding derivative interpreters but python3 was introduced 10 years ago and the python2.7 is legacy.
Perhaps the group should establish python3 for ROS2. At least it’s a place to make a break and set a forward direction.
Addendum: I have been corrected. ROS2 is using python3.