JP II did something similar with Hunthausen in Seattle years ago. The difference was that Hunthausen was a lefty heretic, and was given the co-adjutor because of his “weak doctrinal leadership”. He was given an auxiliary with special powers, Donald Wuerl (yes, THAT Donald Wuerhl), and a co-adjutor, Thomas Murphy.
Back in those days, Wuerl was considered a “conservative”. He played his part well.