The season hasn't gotten to the middle so we still expect anyone to claim the title. It won't be a surprise if Bayern Leverkusen start dropping point after the winter break. This has happened to Dortmund recently where they win almost all their games in the first halve of the league and leading Bayern with some point that makes them stand at the top of the table. Not long after the winter break, they started losing and dropping points until Bayern came from behind to claim the league title. I will only be rest assure of Bayern Leverkusen performance after playing winning some matches played after the winter break.
Personally I've still not put any form of certainty on any one to win the league title yet, regardless of how well some teams have performed because I know until the last two weeks of the league, there are still too many uncertainties and so much can change before then and teams will possibly loose form while the others may possibly gain more form aswell.
It's possible Bayern Leverkusen loose form after the winter break and it's still very possible they will maintain their form knowing how much of a chance they have currently and are not willing to loose form and losses the opportunity to winning the league title but then it's very likely Bayern Munich might not defend the league title this season, but after the winter break then we can be very Sure of what team will have a better chance or will the top team be able to maintain their form and continue in this pase.