What are the implications of Janus v. American Federation (2018) on teacher unions today?

Read Janus v. American Federation (2018) from the U.S. Supreme Court.

Teacher unions have long been a discussion of educational legalists, continually weighing the pros and cons of the longstanding activist groups throughout our nation. In 2018, the Supreme Court ruled on whether these groups, directly or through the state, can force non-members to pay proportional costs of the collective-bargaining activities.

What are the implications of Janus v. American Federation (2018) on teacher unions today? Should a state be legally allowed to include a provision in a public-sector collective-bargaining agreement that requires non-union members to pay the proportional costs of the union's collective-bargaining activities? Why or why not?