All of the major unions have been broken, with the public sector unions coming up next re: the Janus case. Even though there was always a limited number of union workers, their collective bargaining set the standard. That’s not really a factor these days.
Looking at places like Connecticut/Illinois/New Jersey it is causing starvation of public services to meet pension obligations despite already high taxation.
They are caught in a trap since if they raise taxes further (and/or decrease services) they will lose those most capable of moving- who also happen to pay the most taxes. This is already starting to play out[1].
Private sector unions are tasting the fruits of their corruption via the mafia and general unwillingness to integrate with long term industry needs, ala the German model.
Its incredibly unfortunate, since a modern, ethical and foresightful private union would serve the greater good of the country better than just about anything else I can think of.
0: https://www.forbes.com/sites/adammillsap/2016/06/01/public-p...
1: http://www.courant.com/opinion/editorials/hc-ed-tax-migratio...