Only Bayern Munich is not having any problems currently, and they will maintain the standard of the team or buy one or two additional players to add more strengthen to the team. Leverkusen has a new coach and some players are leaving the club, while Dortmund isn't in their best form and needs to sign more players to strengthen the team. I believe that Bayern will continue dominating the league.
Although there is a possibility for Bayern Munich to continue to dominate the Bundesliga, you should not underestimate Dortmund who were slumped at the beginning of the season but were able to rise again with their new coach towards the end of the season until Dortmund managed to rank in the top four in the Bundesliga this season. And for next season I think Dortmund will make their players more ready while looking for some new players to improve their strength although I am also a little less sure that Dortmund will be a title contender for next season.