I seriously doubt he’d ever jump to our ship. He may take a ride with us on occasion, but wouldn’t take up residency, IMO.
I think he’ll stay an Indy, and if he is defeated, he’ll retire.
If the Democrats don't recognize his seniority he'll just be a junior member of a committee. But some Dems want to expel him from the caucus, which would mean that he would not be a member of any committee.