The opportunity for Xabi Alonso to regain or defend the Bundesliga title is still there, or still wide open for him, but perhaps the problem is that most likely this season will not be as easy as last season, but after we see how Bayern Munich performed with their new coach along with Leipzig's impressive performance and Dortmund is also included in it, then I think I can't be sure or guarantee that Leverkusen will be able to defend the title they previously won, Bayern Munich, Dortmund, and Leipzig started the season without losing, but of course it is too early to conclude the overall strength of the team when the season has just started, meaning changes or shifts in position in the standings are very possible.
I also think Leverkusen led by Xabi Alonso can still win Bundesliga title but it will be tough. This season Bayern Munich, Leipzig and Dortmund are playing very well. Leverkusen won the title before but it is hard to do it again. Bayern Munich has new coach and Leipzig is playing amazingly. Dortmund is also strong.
It is too early to know how the season will end. These top teams have not lost yet but that can change. Injuries, team problems and strategy changes can affect team success. Leverkusen needs to play consistently and adapt to stay in title race. Alonso leadership and tactics will be crucial.
The Bundesliga has only played 3 of their matches so far so it is too early for us to say a team worthy of winning the Bundesliga at the end of the season, but even so of course clubs such as Bayern Munich, Dortmund, Leverkusen and Leipzig will not be able to us get rid of the favorite team to win the championship, compared to the previous season, it is clear that if it looks like this season it seems that the competition for the championship trophy will be very competitive because many teams has improved both in terms of quality, performance and also their consistency in playing, Leverkusen was a team that surprised us last season even though they have suffered their first defeat in the league but that does not mean they are has out of the championship path this season.
All teams in the top 5 of the Bundesliga except Heidenheim will play in the Champions League, so they have a tight schedule in addition to having to stay focused on the Bundesliga and also the DFB pokal, consistency and game performance will obviously depend on the strategy applied by the current coaches, so I think to still be able to compete in 3 different competitions the coach will have an important role here to rotate and avoid injuries to his players, the coach ability to formulate a team strategy will have a big influence in maintaining their chances of winning the Bundesliga this season, so we can see who teams that are currently in the top 5 who are able to be consistent in a tight schedule of course will have a greater chance of winning the Bundesliga at the end of the season in my opinion.