Certainly Bayern Munich will not want to lose Musiala, they are not like Dortmund who are a profit oriented club. Bayern Munich will always want to continue winning the league title so they need every good and fit player in the team to help boost the team’s performance this season. I’m unsure about Sane’s position in this team. He didn’t live up to the expectations at Bayern Munich, it is very likely that Bayern will may reduce his wages in the new contract. Knowing Sane’s history at Liverpool, I very much doubt he will take that deal.
Every good team will not want to lose a player like Musiala he is a real gem and of course he is an important player for Bayern Munich that’s why even a team like Bayern Munich will everything in their power to keep him at the club. It is a good thing to offer Musiala a new contract probably with increased wages to try and convince him to extend his stay at the club but even at that there is no guarantee he will not want to explore other clubs. Offers has been coming in for him and if he is interested then he will move but since he is doing well at Bayern there will be no need to make a move out.
Sane is also a good player and even though he is not at his best we all know he has something good in him to offer and i don’t think the new contract proposal will involve a decreased salary.
I can even guarantee that Jamal Musiala is much more important than Harry Kane, last season before Kane, Jamal Musiala role managed to contribute 12 goals and 10 assists so it makes sense for Bayern Munich to keep him longer. If they don't act soon, there will be many clubs who intend to bring him in at any price. He is still young but his maturity level on the field is unquestionable.
Musiala is important and Kane is also important there is no need to compare them both they both contribute positively to the team in their own ways. Kane is a goal poacher and his goals are very important for the club, Musiala on the other hand doesn’t score as many goals but performs some magic to contribute to the team’s success.