Unity v2017.1 released for general access a few days ago has the possibility of .Net 4.6. it is marked as experimental for now, but their release notes say it

Unity v2017.1 released for general access a few days ago has the possibility of .Net 4.6. it is marked as experimental for now, but their release notes say it will become the new default soon I am evaluating 4.6 support now and it works okay so far for my VR Game