Won't happen, parties always adjust to huge losses or it might be the party who just had a huge landslide win just gets over confident thinking the people as a whole love them when they just really disliked the other guy.
Goldwater was repudiated to a tune of a 61-39 win for LBJ in 1964, the Republicans were down to just 140 House seats, 295 for the Democrats along with 68 Democratic Senators to 32 for the Republicans. 1966 saw the GOP gain 47 house seats back and in 1968 Nixon had been elected president, the Republicans had gained 10 senate seats to 42 and now had 192 house seats.
That's a long time ago, I know. Different political era without the polarization and without the ultra high partisanship of today. The rejection of a presidential candidate doesn't equate to the destruction of that candidate's political party.
The rejection of Trump in my opinion began the day after he took office which lead to the blue wave of 2018 and unless something changes, something happens drastically, a major unforeseen event or happening, the Republicans are in for another huge defeat in 2020. But the rejection of Trump won't equate to the demise of the Republican Party much like what happened back in 1964 through 1968.
Gallup and Pew Research never asked about political party favorability back then, but they do now. But they did keep track of party affiliation. Party affiliation in 1964 was 51% Democratic, 25% Republican. By 1968 it was 42% Democratic, 27% Republican. In 2016 when Trump won party affiliation was 36% Democratic, 30% Republican and today it's or as of 4 June 2020 31% Democrat, 25% Republican, 40% independent.
The average political party favorable's is Democrats 30% favorable, 52% unfavorable. Republicans 24% favorable, 57% unfavorable. Neither major party is liked or seen in a favorable light. But the Democratic Party at the moment is seen more favorable and disliked less by America as a whole than the GOP which probably will equate into a huge win come November.
One reason for this is most Americans don't think either party represents them anymore. Each party has it's own agenda which isn't seen as America's agenda. It's very hard for the hard core partisans, member of each major party to see this. Voting for the least worst, the lesser of two evils, the party, candidates you want to lose the least, not win, but lose the least have become common place. Trump will be rejected this November, I'm sure of that. But the election results will be just that, a rejection of Trump much like 1964 was a rejection of Goldwater. But the incoming blue wave that I see coming isn't an endorsement of the Democrats or their party. It's a rejection of Trump and the GOP. It's not a mandate for Democratic Party agenda either. It's a rejection of Trump.
This the Democrats will fail to recognize. Hence my prediction about the house in 2022. But time will tell.
It's high past time that we start electing Americans to congress and the presidency who put America first instead of their political party. For way too long we have been electing Republicans and Democrats who happen to be Americans instead of Americans who happen to be Republicans and Democrats.