In short, it wasn't so much Goldwater's drop ~ but more LBJ's gain!
That's the permanent majority that ended with Richard Nixon's victory in 1968! Buchanan, however, sees the new majority starting with Ronald Reagan although that simply heralds the permanet lodgement of the white Souvr'n voters in the Republican tent.
It is difficult for either major coalition party to advance much beyond 50% + 1 vote for long. There's not going to ever be a string of landslides like Thomas Jefferson and his friends enjoyed in the early 1800s. Our factions rejust quickly ~ right now we have a shot at UNEMPLOYED BLACK VOTERS so we needed a jobs plan to beat the Democrats over the head with in 2012.
Didn't happen. That opportunity was lost. But it's not too late for 2014, and 2016. The Great Obama Recession isn't going to end that quickly, the US is going to have used up its overseas credit with ObamaKKKare borrowing, so no more gub'mnt operated jobs programs.
We can get back that 25% and maybe more EASILY. Unfortunately the GOP-e has no will nor interest in building the party and registering new Republican voters ~ particularly unemployed black men.
Man, sorry to tell you that LBJ won in a massive landslide that covered all categories, it wasn’t the black voters moving from 75% to 94% democrat, and it wasn’t better black turnout, and it wasn’t anti-semitic Jews voting 90% for LBJ.
Goldwater lost everyone, including 60% of men and 59% of the white vote.