Manuel Neuer is indeed a great goalkeeper, but he also has to hope that the players in the defense have to be good so that the team doesn't concede too many goals. Because no matter how good the goalkeeper is, if he is continuously attacked by his opponent, in the end he will concede goals, so a good goalkeeper is necessary, but the players must also be better so that the squad can have complete strength.
there is no doubt that the position of Bayern Munich defense line has been overhauled with several new players and if you look at the pre-season matches at that time it was better against Man City even though they lost but do not concede too many goals. even though Manuel Neuer has just recovered from injury, I am sure that Neuer will still perform well in the summer because we all know that this goalkeeper is a mainstay and there is no doubt about his performance, so Im very sure that Bayern Munich will have a strong performance this summer.
I understand that no matter how good a goalkeeper is, if the defense is not too strong, there will certainly be a lot of goals conceded, but lets see if my prediction is right or wrong, Im sure Tuchel has a good strategy when he knows that Neuer has just recovered so he will use a defensive formation.
Bayern cares about defense more than they care about offense, they are a strict team and not getting scored on is an important part of the game. if you never concede then you never lose, worst case it's a tie. That's why they keep getting better and better players whenever they can to defense, and keep improving it, hell even get same level player but younger to be better for longer.
So all in all I am guessing that it's going to take some time but if it's possible then it can be tried out. I know that it will take some time, but focusing on what you can do with whatever you have is something they do great. Now that Mane is basically gone as well, they can get another player and that will make them even better as well.