If Bayern Munich do not achieve the maximum this season, it is entirely their own fault. Bayern Munich is a full team this season. The team management has not left any weakness in this team so it is natural that their expectations will be the highest with this team.
Bayern Munich have looked consistent in the Champions League so far and they will look to maintain their consistency in the Champions League. Besides being consistent in the Champions League, they need to be a consistent enough team in the Bundesliga to win the Bundesliga title as well as do well in the Champions League.
We won't be surprised if Bayern Munich win the Champions League and Bundesliga this season.
The key is for Bayern Munchen to be consistent and focused on getting points. Tuchel has a tough task to make FC Hollywood continue to dominate the Bundesliga. Improved performance of Laberkusen, Vfb, Dortmund and Leipzig could be a real threat to Munchen, Laverkusen leads the top of the points table and Vfb is below it, with a difference of 2 points. Munchen must be willing to sit in 3rd place in the standings. I think it proves that this season is more competitive than the previous season, Tuchel has to be really alert.
Even though he is the favorite in the two competitions UCL and Bundesliga, sometimes bad results can happen at any time. With two consecutive wins in the group phase making Munchen lead the Group A standings, I think Munchen can easily qualify for the last 16 with group winner status and get perfect points.
Of course that's what Bayern Munich must continue to do now, focus on achieving higher points. The Bundesliga this season is indeed more competitive, many teams have shown their true strength, as you have mentioned, especially for Leverkusen who initially occupied the top position and then shifted down again and now Xabi Alonso's squad is able to return to the initial position which is the leader of the standings. The top five is indeed being dominated by very strong teams now so of course this is a very big threat to Tuchel's squad as defending champions in recent years. Honestly, I would not say that this season Bayern Munich is weak because of course the competition is now tighter because some strong teams have shown dominance in the last few matches. I agree that this is indeed a very difficult task for Tuchel. I don't know what action Tuchel will take next, but surely he must be able to excel so that their title as defending champions can continue.
It's true that the results cannot be fully predicted even though Bayern Munich can always be the favorite team in the Bundesliga and UCL, but that cannot be a reference for the results at the end of the season, still as you say anything can happen there, to qualify for the last 16 I believe the door is wide open for Bayern Munich.