I would say this season's title battle is only between Leverkusen and Bayern Munich. I don't think Stuttgart, Leipzig and Dortmund teams are fit to win the title.
The performance of the Dortmund team has been very erratic this season. Dortmund are now 15 points behind Leverkusen at the top of the table. It seems impossible to me for Dortmund to close this 15 point gap. Because the performance of Leverkusen is very consistent, on the other hand, the performance of Dortmund's players is erratic.
The Stuttgart team was in good form. But in the last four matches, they lost 5 points and fell far behind. The team would have been able to continue competing for the title if they could have achieved these 5 points.
It might be premature to completely write off teams like Stuttgart, Leipzig, and Dortmund from the title race. Dortmund have a history of making comebacks. Football seasons are long, and teams can experience fluctuations in form, especially Leverkusen who don't have a good quality depth. Dortmund has the talent and experience to turn things around, especially if they address any issues affecting their consistency.
RB Leipzig have a strong squad, and if they find their rhythm, they could mount a challenge for the title. Never underestimate the capabilities of a team that has consistently performed well in both domestic and international competitions. While Stuttgart may have lost some points in the last few matches, if it's due to temporary issues like injuries or fixture congestion, the team might bounce back and regain their form. Unexpected results, injuries, or changes in strategy can significantly impact the dynamics of a title race.