He'll trash certain individuals definitely, but he will still want some presence in the party's future and they know that too which is why the GOP having some sort of epiphany of sanity should he lose is so unlikely.
Sanity was never going to happen no matter what. It didn't happen in 1992 or 1996, it didn't happen in 2006 or 2008...so why now?
Some people probably are still foolishly clinging to this notion. It's why seeing anti-Trump Republicans who may cling to the "supporting a Democrat for President but with a Republican Senate to check them" mentality are so frustrating.
Those people really only exist on this website, not the real world
For this year, sure. But in looking at how down-ballot candidates like Russ Feingold under-performed Clinton in 2016, they were definitely a presence then and foolishly screwed the country over even more by being so presumptuous about Clinton winning and not considering how a continued Republican Senate Majority would enable Trump so much.