Drew Furgiuele digs into why Powershell scripts break with SQL Server 2016:
One of the steps I tried to remedy the problem was removing the SQLPS module directory from the PSModulePath environment variable, to see if the Import-Module would skip over it. Turns out I was only half right: I should have removed non 2016 versions of the module path, as Matteo goes on to explain:
I’m hoping there will be a real fix for RTM. This works, but it’s neither intuitive nor easily decipherable.