I hadn't even considered this. If the Senators on both sides hold steady this could happen, as far as I know there is no way for the house to do anything. And even if they could, Johnson is refusing to seat Grijalva due to the shutdown and so he could try to do the same with the 120th Congress.
my showerthought today was "I wonder if the Dems are willing to fall on their sword for this. Either they protect the ACA or they can force a destabilization of the administration with plausible deniability, even if it costs them their careers." but no, I can't imagine that many career politicians in a mainstream party would willingly conspire to commit seppuku
@AlanTennant the biggest forcing-function to bring Trump to the table are probably air traffic controllers. I do wonder though if he'll just post them through emergency order or if states will step in to pay them.