Dortmund had their biggest chance of winning the title last season in the last 5/7 years. Had Dortmund won the last match, they would have been Bundesliga champions. But they failed to get 3 points in the last match. Perhaps this is why the Dortmund management wants to fight for the title next season. Dortmund management has the ability. They have talented and promising young players in their squad. However, if they want to win the title, Dortmund management should make the squad a little stronger by making big funds. Bayern Munich's squad is very strong. If Dortmund's squad is not strong, they will not be able to compete with Munich.
There are two factors here, the first is that Dortmund will never invest so much money to buy expensive players, everything works the other way around for them, they buy promising players and sell them expensively. The second is that Bayern spent the end of the season very badly and lost a lot of points, but this gave Dortmund a chance to get closer to Bayern, whether this situation will happen again is unknown.