There has been plenty of speculation about whether reaching adulthood will open the door to a move abroad.
Real Madrid are regularly linked, Barcelona are frequently mentioned and Paris Saint-Germain are known admirers.
But Bayern now have the opportunity to make a statement of their own with a new contract.
The German club have long been determined to ensure his head is not turned, taking careful steps to make him feel central to their plans and fully integrated into their set-up.
Karl has started five times in the Champions League and 11 times in the Bundesliga this season - a clear indication of the trust placed in his talent and the belief in his vast potential.
Now the moment has arrived to formalise that faith by improving the terms of his commitment.
It is expected that, following his 18th birthday this weekend, Karl will commit to a new deal tying him to Bayern until 2029.
Beyond that initial agreement, there are already plans to extend his stay even further.
The reality is that Madrid, so often linked with the teenager, have not managed to turn his head at this stage. Much of the speculation stems from the player previously naming them as a dream destination for the future.
In recent months, however, there has been no active push to engineer such a move. Possibly because there has been such a firm notion from Bayern that he will not be leaving.
Premier League clubs are frequently mentioned as well, with Arsenal, Chelsea, Liverpool and Manchester City maintaining contact and monitoring his situation.
For now, though, midfielder Karl is set to show loyalty to Bayern - focusing on his development and continuing to make his mark on the game.
