Well, if you're using him for his mystery and cc on chase, both Kurama and 6PN are better replacement since they hit more targets, and can fire off mystery every round, not every 2 rounds. His clone and revival passive aren't really very important late game. Edo Hashirama is also a possible replacement for Mu, since his mystery is undodgeable, hits 12 units, and his chase both immobilized and steal all chakras. All 3 of them requires serious saving, either cps or ss, but that's why they are late game ninjas.