Also, Article I requires there to *be* a CJ, but does it have to be a sitting member of SCOTUS? Couldn't Cong vest the role of "Chief Justice of the United States" on, for example, the Chief USCJ with the earliest date of commission? (Or for that matter the senior-most judge picked by sortition?)
The hinky part there, to my mind, is the fact of Roberts’ confirmation to the role of chief justice. I’d rather avoid the vulnerability of having to litigate his claim to the title. (That said, I also welcome making him captive on a court yanked from his control — made superfluous, as a punishment.)
I agree that you probably can't replace the current CJ in this model. Any change to how that title is vested would have to be effective upon his death or resignation.