If you are referring to the 2016 election, at the time Obamacare was not in danger at all and it was working fine for me.
Moreover, I can't really recall everything Hillary said, but I'm not sure she said we'll never have universal health care. She may have said something to the effect of, with republicans in today's political climate it was not something feasible, but it is something we could work towards. Or she may have said what you said, I don't really recall.
As for it's constitutionality, I really wouldn't know but I don't see why it would be unconstitutional because we have to buy other insurance. I know I have read the argument to that, we don't have to buy a car, (try living in the country without a car..)but you do at some point have to have medical care. You don't if you chose to just die without medical care. So I am not sure that argument holds water.
If we could get enough democrats in both houses and the WH, after so many people have experienced the advantage of Obamacare, I think it is very feasible to finally have universal health care. However, we would have to pay for it and you can't really do it on the military alone (seems there are charts, will look them up if required) so people will have to pay more in taxes. It is the way they do it in other countries. (Israel for example) People shouldn't have to chose between having a secure nation and health care. Not saying we couldn't cut down on military spending, just getting out of the wars would be a good start and necessary on it's own and for our own security.