Yes, this is an unusual season and there is a possibility that we will see some unexpected champions in the European championships - for example Roma or Udinese in Italy 
But I doubt that this is possible in the Bundesliga. No matter how bad Bayern play, all competitors will play even worse and less consistently. In some segments they can show good results, but in general they are untenable.
I also think Bayern Munich still have the best chance of winning the title despite their poor form. Because if Munich can return to form, they will win all the matches consistently and occupy the top spot in the table. But I fear, if Union Berlin is able to continue their streak then it won't be easy for Bayern Munich to win the title. Not only is Union Berlin at the top of the points table, but their performance is also excellent right now. They scored 15 goals in 7 matches and conceded only 4 goals. Union Berlin now has the strongest defense in the league. If the defense can keep this strong, Union Berlin will be able to maintain the top spot on the table for a long time. But I doubt that this is possible in the Bundesliga. No matter how bad Bayern play, all competitors will play even worse and less consistently. In some segments they can show good results, but in general they are untenable.Miracles like Leicester do happen sometimes but they are very rare so I find it ridiculous to discuss the prospects for Union Berlin. It is far from a fact that they will even get into the top three teams at the end of the season. Look at bookmaker quotes for the championship:
Bayern Munich 1.14
Borussia Dortmund 9.75
RB Leipzig 27.90
Union Berlin 41.00
I think their current result is a mixture of a good calendar and good luck in the games, but further distance will fix it all.