There will be challenges but they’ll have to go to the federal level but I don’t see them getting far because the union has no valid argument.
They can scream, cry and whine to the public about how this strips them of collective bargaining rights but there isn’t a court in the land that will buy that propaganda.
This goes to the heart of unionism. They will band together in solidarity and fight this hammer and tong. It will be dragged out in appeals and as many other delaying tactics as you can imagine. The union bosses know their very existence hangs in the balance. They will never give up and it’s going to get very ugly. I spent half a career fighting these MFers. They are ruthless.