Well it has to be one of the three branches. If not the Judicial then the Executive? You want to have a Monarchy? What is feasible is a Constitutional amendment limiting Federal Judges to one 12 year term.
Term limits work for other politicians, why not judges?
A 12 year term limit would give judges the "independence" they say they need, while automatically limiting the damage any one judge can do. It also has the benefit of bypassing a do-nothing Congress.
I could get behind a limited term for Supremes. It seems the longer they sit the more power mad they become. This is demonstrated by how long each and every one of them hangs on to his position before retiring.