Just my opinion, and maybe it's just wishful thinking, but I do feel like Lewandowski, Müller, and Neuer are generational talents that will be extremely difficult to replace when they leave/retire. I tend to think that Bayern's grasp on the league has slipped in the last couple years and their titles have been more a function of other teams failures than Bayern's successes. That being said, it is true in that Bayern's consistency when it comes to winning the tough games is something that the competition doesn't have. Leipzig, Dortmund, Gladbach, Wolfsburg, Frankfurt all dropped points against each other and lesser teams down the stretch whereas Bayern grind out the results even when playing poorly.
Back to my original point... Bayern will still have talents like Kimmich and Goretzka but replacing Lewandowski's goals and Müller's assists will be extremely difficult, even with a budget that no one else in the league can compete with. Manuel Neuer is arguably the best goalkeeper in the world. I'd like to think that the gap between them and the other teams is getting smaller as those players age.
Interested to see what @Viva la FCBwould say about this.