If not Leverkusen, maybe Stuttgart will be a contender for the Bundesliga title this season because they are performing well and they can even finish in 2nd place, although perhaps towards the end of the season Bayern Munich's performance will no longer be as optimal and it might be a different story if there is no Leverkusen name at the top of the standings.
It's hard to predict. The Club's condition will still be affected by the transfer market. I think Bayern will remain in the top flight with Dortmund, Leipzig. Then about Stuttgart and Leverkusen they are the teams that make a surprise. Judging from last season there was a big change, Stuttgarat is a team in the Relegation Zone, but they were able to survive and this season we have seen that. Then Union Berlin last season was quite competitive, this season they dropped quite far at the bottom of the rankings. The German league seems to be too competitive for dominance of the top 5 teams, so it is difficult to determine who will continue to perform great and end up at the top.