G Dub actually championed a very reasonable model of SCOTUS term limits of something like 16 years, with an option to step down/retire and only become eligible again after the appointment expiration or retiring 4 years later.
There was a model for phasing out current members if such a policy were to be put in place (which, I think, was for them to just serve out their natural grandfathered term).
Once in place, the rotation of appointments would be such that every president gets about one appointment per term, with no more than 2 possible appointments for a 2-term POTUS.