It would have been completely different without JFK getting us into the the Vietnam War, Vietnam was a truly major war that introduced and maintained the chaos the domestic and international left needed to work with, his assassination, LBJ, Vietnam, without those America would have remained far more stable and unchanged.
Getting into Vietnam was not the problem, the problem was the infiltration by the Communists in our institutions had taken root and make the war unwinnable.
We could have won Vietnam easily with our military, but the political will to use the full force of our military was no longer there when you had the media and the academia acting as fifth columnists sabotaging the war from within.