All depends on how we start next season imo. Not really in terms of results, more in terms of how the players respond to winning four titles in a row. If he can sense they're committed he'll probably do 10 years and call it in 2026. If he senses the atmosphere and hunger has dropped he'll probably call time on it all next spring.
At which point we'll know how Xabi Alonso copes as a Champions League manager - if Leverkusen are on for another Bundesliga title and in the last 16 of the Champions League we'll probably take a punt on him. If not we might be looking at Gasperini or Enrique or Simone Inzaghi. Just for 2-3 years. Then we'll plan again.