I wasn't suggesting he could be gotten on a free, but perhaps Bayern could be tempted out of respect for his servitude to the club to leave for a respectable fee. Unlikely I know, but if the player is vocal about wanting a new challenge then they could possibly entertain it. Currently they're valuing him at around £100million (which is absurd given his age),
but perhaps a smaller albeit respectable bid, coupled to their club legend's sincere wishes to have one last go at a big league might tempt them to oblige his wishes.
I was going to bring up Schweinsteiger as an example of when the club respected one of their legend's wishes to leave, but in hindsight I best not