I totally agree with you. Thomas Muller has done so much for German football and now it is time to give younger players chance. He has had amazing career winning many awards including the Golden Boot. He is legend in German football. He might keep playing club football but he will probably stay with Bayern Munich until his contract ends. He might consider playing outside Europe but it is unlikely he will join another European club. Muller time playing club football might be coming to an end but his legacy will live on. New talented players like you mentioned Jamal Musiala will carry on his legacy and inspire the next generation of German footballers.
Thomas Muller is such a big name in the German football and also a big name in the Bayern Munich’s Bundesliga league. He has achieved greatness all his years in football for club and country side. I can’t even remember him playing for any other team asides from Bayern Munich since I started watching him. It is indeed an high time for him to retire from international football and be playing on club side peripherally before he finally retires football fully. He should have a lot of players that are looking up to him that want to be like him, he has lead a good road path for young footballers and his legacy will never be forgotten in German football and Europe entirely.