Never go to happen. All of those people with employeer paid insurance would march on Washington to take their congress person out and lynch them if they took away their health insurance and then expected them to pay taxes to get what they were getting more or less for free.
I find it amusing that so many people assume that it is the "greedy, evil corporations" that want to leave the USA behind for cheaper places at which to manufacture their goods.
It is ALSO (and probably largely) the fault, however, of government regulation and interference that is doing it. With city, county, state and federal taxes on everything they do, with restricting regulations and with the ancillary costs such as defending against scum bag lawyers and unions, they spend so much of their efforts and capital dealing with this stuff that they eat into their profits horribly.
We could make the USA business friendly again, for one thing. That would keep a lot of corporations from leaving.
It will happen. Free trade will FORCE the introduction of national health system. Mark my words.