It wasn't a good time to be a liberal in the 80s (even the word was frowned upon) and liberals tried to moderate their beliefs to court the center (really Clinton was probably slightly to the right of Nixon domestically). It's worth keeping in mind that the 1930s-1970s were virtually the only mostly left of center period of politics in the US since the Grant administration and began the Conservative period of dominance, which I think will probably be viewed as, despite Trump, coming to an end with 2008. The current growth in more progressive beliefs is probably still a delayed reaction to 2009, to which Conservatives managed to mute the response. Since my prognostications are never great, however, feel free to write your own future.