My expereience working under a mandarory union was this:
I had to pay dues not only for union healthcare benefits, I also was protected with worker's rights. Rights to be sick, to not get in trouble if OT occured, senority for fairness in holidays, progressive leadership equality. I learned alot about the "union", only because after exhausting all my options on a particular issue did I then have that outlet, to have orginazational people come in and go to bat for me and make sure the rigts(contract) was inforced, or the company faced penalties.
Unions now I belive are looking out for the nurses and blu collar guys and all types of jobs to do just this, to protect from unjust treatment. Healthcare is just part of the package. I don't know the answer as to how their interaction with the gov'tor HC institutions will be, But I can bet they will be there. IMO.