A significant number of people, mostly Trump supporters, don't realize that the Affordable Care Act and Obamacare are the same thing.  At least some Republican lawmakers seem to want to repeal Obamacare and replace it with the Affordable Care Act.
In 1960, the topic for high school debate competition in the United States was universal health care; the point of departure was the program in England, where universal health care had been in place for about ten years. As you say, the issue has been kicking around a long time.
You're right, too, that Obamacare is an adaptation of Romneycare, which in turn grew out of Nixon's efforts to provide a conservative alternative to the progressive proposals of Sen. Ted Kennedy and the Democrats. The reason the Republicans are having such a hard time coming up with a conservative alternative to universal health care is that the Affordable Care Act IS the conservative alternative.