The Bayern Munich team has been really lucky this season. Because this team did not perform very well in the last stage of the league, on the other hand, if Dortmund had not drawn with two goals in the last match, Bayern Munich could not have secured the title.
It is a thing that has passed and can only be remembered as history by Dortmund. And because Dortmund have almost managed to get another trophy in the Bundesliga, that means that Dortmund still have to try to do better next season by winning more every game since the start of the season so that Dortmund can more easily secure themselves to become champions again in the Bundesliga. Because competition in the Bundesliga is fierce again and next season is unlikely to be much different from this season.
The German Bundesliga season is over already but Borussia Dortmund's failure to end Bayern Munich's dominance in the league will surely hurt the fans of Dortmund now and in years to come especially after seeing how close Dortmund were to winning the Bundesliga title.
Dortmund's transfer dealings of selling their best players to other European clubs in almost all the summer transfer windows I think is another reason why they shouldn't be considered as a strong team to compete with Bayern in not just this season to come but in years to come.
The dortmund team built not to win the title , every year ... every season they are building a team from a scratch as they tend to sell the players even to the rivals in order to gain profit from selling players , that's an usual practice for dortmund , the board might won't feel anything even if they consecutively failed to get the bundesliga title but the fans indeed will always feel betrayed , the club must honor everything on fans side as the club mean nothing without the fans / supporter.
Such an irony situation , dortmund could become the greatest clun in europe if only they keep all the key players.