I don't doubt Xabi Alonso because what they got this season is the result of his hard work since last season, not just luck, so it is possible that this can continue or even get better.
The heavy pressure next season will definitely be from Bayern Munich who will grow even stronger to compete for the title and of course that will make the Bundesliga competition even more competitive.
I guess it will be cant getting better as they have played the whole season of the german league and its hard to top that.
Leverkusen have to proof themself now in the Champions League , but i think that they will be doing that.
Bayern Munich for sure have already the pressure and with the change of the Coach and few players leave it will be not easy.
Leverkusen need several additional players to strengthen their squad next season, this needs to be done to play at a higher level, it seems that Atalanta and Leverkusen are in the same competition next season, namely the UCL, if they meet again there is a chance for Leverkusen to avenge the defeat them, but don't think too far like that, what Xabi Alonso has to think about is how he convinces his players to be consistent again next season like this season throughout their journey without defeat in the Bundseliga, which is a good achievement.
On the other hand, it is true that there have been changes in the players and coaches in the Munich camp, obviously this will also affect their adaptation process on the field, but Kane certainly doesn't want to experience failure again next season, he will play as hard as possible to be able to bring Munich to success. trophies next season, the most important trophy is the UCL and the most targeted trophy for both of them is the Bundesliga and they will dominate again like in the previous season, Leverkusen will also of course experience very tight competition next season and Xabi Alonso has certainly thought about that. .