This year Borussia Dortmund was worse than expected, maybe next year we can watch them join the championship race. Bayern Munich will want to make this year's defeat forgotten next year. I'm sure they will build a great squad next year. The coach who will replace Tuchel has a lot of work to do. He has to focus on strategies that will bring Bayern back to its feet.
Dortmund shouldn't have had quite a lot of defeats or draws, such as against Hoffenheim, Wolfburg or Heidenheim, so they have lost a lot of points in that time. But when they play against teams that are equal or stronger, like against Bayern Munich, they can actually win. Dortmund's results have been inconsistent and it is only natural that this season they are having great difficulty in competing for the title.
Regarding Bayern Munich, it might be a difficult season where all the criticism will be aimed at them this season and of course next season they will still have doubts from football fans. It is still a question whether they can win the Bundesliga title again or not and maybe Bayern Munich's new coach will be under a lot of pressure from fans about that.