I agree on that with a young and very good goalkeeper and have an eye on the first goalkeeper when Manuel Neuer will end his Career.
But that will be hard to find for sure , and i dont know if Alexander Nübel will be like it to be again the second one when Neuer is coming back.
That was the reason why he wanted to play at other Club.
Apart from Nubel, I think Bayern Munich seems interested in the Argentinian goalkeeper in the World Cup - Emiliano Martinez to be their main goalkeeper this season. Neuer looks set to be out for quite a while due to injury. Nubel seems to have no more interest in returning to Bayern Munich, but anything can happen in the end. So it's true, Nubel may not want to be a substitute player who sits more on the bench throughout the season.