I'm not subtweeting @RadioFreeTom not least because I just specifically named him, but a thesis I've seen him and others expound is that the only way to drive Trumpism from the GOP is to break the party, which will teach the dumb animals not to touch a Trump.
I find this theory dubious in mechanism and history, so I took the first offered example: Votes against the Democratic Congressional party in the 1980s as the driver for the Clintons (as opposed to being pasted repeatedly at the Presidential level for decades).
Using the initial, post-election compositions of every Congress from the 96th (1979-1981) through the 101st (1989-1991), we can see if widespread party destruction at the Congressional level was real; from there, we can argue over whether that drove Clintonism.
(This puts to the side for the purpose of this analysis whether Clintonism, which was a project beginning in the mid-1980s and before, achieved national recognition by the 1988 Democratic Convention as a force because of Congressional, Presidential, or societal events.)
Democrats owned the House of Representatives during this decade; even Reagan's landslide wins were not enough to drive them even to the point of hanging on by the molecules on the edges of their fingernails. 
(Side note: Yes, it should be Reagan Blue, Commie Red, I'm exhausted and not fighting Excel over coloring.)
The Senate is different, sort of. Reagan's win in 1980 broke Democratic control of that House (who here remembers Alfonse D'Amato? Don't raise your hand, we're all embarrassed enough as it is), but the Democrats started regaining seats and won it back by the 100th (1987-1989).
The counterpoint, which I'm too tired to graph now but might in the morning, is the Congressional AND state-level Democratic Party under Obama, both of which enjoyed a renaissance that began under Bush and peaked on Obama's election ... and then collapsed and kept collapsing.
Democrats lost, in rough order, the House, the state houses, the state legislatures, and then the Senate. This did not stop Barack Obama from being re-elected; and it seems not to have driven Democrats to the conclusion that they had taken a wrong turn EXCEPT WITH CLINTONISM.
Now, time for fruit comparison and oh I struggled not to make a joke there. It may be that Republicans now are appreciably different from Democrats in 1980-1992 and 2009-2016, and will be so horrified by national legislative losses that they'll change.
But first, this overlooks the fact that the Senate has essentially become a blocking and appointment mechanism for the Presidency, the House just the keypad on an ATM, and real power lies in Article II (sometimes even the President!) and Article III, so the motivation is diffuse.
Second, while it may be that Republicans are appreciably different than Democrats, there is no real evidence this is so.
All of this is to say, Tom and others I've seen advance this hypothesis may be right, but the actual evidence seems sketchy at best. So: Vote your conscience, not invisible mechanisms of dubious provenance.
