I believe they will still maintain that top team next season, because their players are still fully ready to remain in Borussia Dortmund to correct the errors that made them to miss trophies, and they have what it takes to win the trophy but they allowed errors to occur that stop them not to achieve the trophy.
I guess many people know how the tournament ended, which Borussia Dortmund players try their possible best to maintain a good position from the tournament to make their fans celebrate despite they didn't lift the trophy.
That is one thing many football fans fail to understand. In as much as I know and understand the importance of winning a trophy to maintain and protect the relevance of a club, it's not the only basis to rate a team and their success level. Sports is not just about winning a trophy, it's all about performance. Most at times, the performance translate to winning a trophy but that is not always the case. Winning trophy is some time attributed to luck and not by the hard work. Borussia Dortmund even without winning a trophy has shown a spirit of dedication, improvement and commitment to take the club to another level.
Take for instance, Manchester united with a trophy this season but the performance has nothing to write home about. Arsenal too, without a trophy despite their impressive performance. Trophy is just a symbol of appreciation for reaching the end of the competition but it is your performance that define who you really are. Dortmund have paved way for themselves and would definitely walk easier in the coming season if they continue with such energy.