Good post - I believe the real answer is that the left never expected to lose this election. I firmly believe had Trump not won the nomination (despite their confidence in opposing him and even hoping he did) we would have another President Clinton in the White House and a far different court.
I believe Justice Thomas may retire given past comments giving Trump another chance to find a younger candidate.
There is another bonus for the coming shift on the court - Justice Roberts may be pulled in the right direction - he seems to love consensus on the court and it is a powerful force so a more conservative court will most likely have influence on him.
There was one account I read which posed the theory that the White House knew that Roberts was not a fighter, and that if enough pressure were applied, he would buckle. If that was true then, I hope it’s true now.