In the meantime
Sven Ulrich, their second goalkeeper will take over the position of Neuer. Bayern will find one goalkeeper from transfer market because with only two goalkeepers, it is risky. They can get injuries in a second half of season anytime and if both goalkeepers are injured, it's terrible.
Sommer, Livakovic and Emiliano Martinez won't have too expensive price on transfer market.
It seems that Bayern Munich is only planning to add another goalkeeper in the short term. Yann Sommer is 34 years old, as is Sven Ulreich. So it seems that Bayern Munich assume that Neuer will be back in the goal next season. I think that Yann Sommer know it too. Therefore, I can not understand why he should change.
A transfer of Livakovic would make more sense.