The situation might be a little different because they just had a change of coach and some talented players moved to other clubs. Dortmund have to start from scratch this season because the players have to adapt again to the new coach and some of the newly brought in players also need time to adapt to the new atmosphere around them. The increasing competition in the Bundesliga will make it difficult for Dortmund to compete in the top four, Leverkusen is still a candidate for the title this season after achieving great success last season.
Bayern Munich are also starting to build their squad after a less than impressive performance under Tuchel, Stuttgart will also try to provide competition after finishing below Leverkusen last season. The competition in the Bundesliga is getting more interesting after Bayern Munich dominance was broken, now there will be other teams who want to follow in the footsteps of Leverkusen who have just won the Bundesliga. In my opinion, Dortmund still has the capacity to enter the top four, but the chances are very small.
It will not be too difficult for Dortmund to be able to enter the top 4, as it has happened since the past that this team is consistent enough to stay in the top board but they are not competing for the title.
Indeed Dortmund with their new coach will have a little difficulty but I don't think it's excessive.
Leverkusen and Bayern Munich will still be the favorites to win the title this season and I even think the competition this season will be much fiercer because Bayern Munich made many changes in the team.
And overall the competition in the Bundesliga has been quite fierce in the last few seasons we can see that the Bundesliga is getting more competitive.