I know it absolutely won’t happen, but imagine if Manchin flipped to the GOP tomorrow, like the amount of hysterical press coverage against him that would bring.
But he didn’t flip with a GOP president and a GOP Senate, he ain’t going to do so now, unless the Democrats go so crazy he pulls a Jeffords.
I agree its unlikely, but maybe a little more likely than it was in 2017 for two reasons: (1) The Democrats really are crazier than they were 4 years ago, and certainly not in line with West Virginia voters. (2) There's a big difference between joining a GOP majority and delivering a GOP majority--he may have gotten a pat on the back in 2017, but he can basically name his price to McConnell at this point.
It wouldn't shock me if he became an independent and caucused with Republicans on procedural matters (like Jeffords did) in exchange for a better committee post.