Next season will be a difficult challenge for Alonso in maintaining their performance, because after all the rival teams will strengthen their squad very well, so indeed Leverkusen is also required to do the same by bringing in some new players to be able to compete next season, I personally doubt a little if Leverkusen can repeat their glory next season because indeed tighter competition will occur both in the Champions League as well as domestic leagues.
I believe Leverkusen still has the potential to become Bundesliga champions next season. I put Leverkusen as the first favorite and Munich as the second favorite to win the Bundesliga. But I'm not sure they will be able to win the UCL next season. This season Leverkusen has really impressed in the UEL. They managed to reach the final but unfortunately they lost to Atalanta. Hats off to Alonso who has succeeded in turning a mediocre team like Leverkusen into a very solid squad. Alonso will always be remembered as the coach who came closest to achieving the invincible treble, a prestigious achievement that as far as I know has never been achieved by any coach in Europe, or even in the world.
There is no doubt Bayer Leverkusen could be the toughest team in Bundesliga with their consistency and quality with Xabi Alonso is surely looking for the another memorable season even now situation is completely different because we are having them into Champions League and things could be not on same level, but they can go through for the title in domestic league because they are having enough room and their strength is also good beside we are having few teams which are doing their best for improvement but it is looking not easy.
Game is changing quickly with many teams are having ups and downs but as Alonso and Bayer Leverkusen is keeping their squad without changes it's interesting and challenging because now they are having more challenging matches and teams to face.