Bayer Leverkusen will struggle to make things standing next season because every oppositions they face will likely play their best against Leverkusen. Remember Bayer Leverkusen have one of the current best manager in the European world of football, Xabi Alonso the man that won the Bundesliga title unbeaten and have also dwell more of his valuable time on the squad for the purpose of preparation next season.
It won't be that difficult for Xabi Alonso to improve the depth of his squad again next season because Xabi Alonso only needs to polish several areas in certain lines so that his squad can have better strength next season, such as in the defense area and also the attack area. If Xabi Alonso is able to bring Leverkusen to win the Bundesliga without time, of course it is not impossible for him to repeat this next season as long as the players are still quite united and can still carry out Xabi Alonso's instructions.
Based on what they did this season, Leverkusen should be able to compete in the Champions League next season. You're right, he just needs to polish his players and patch up the necessary positions to make them even better. I hope he can do that and lead Leverkusen to achieve something extraordinary in the Champions League. They are a new threat in the Champions League next season, so the opponents they will face will definitely be aware of that.
They have to play freely, don't let the Champions League become a burden for them. Because if they make the Champions League a burden, then most likely they will not be able to show their best performance. Xabi Alonso must also be able to ensure that the players he has are in a very good mental state, so that it will make it easier for him to implement strategies. Because their mentality will also influence them in applying the strategies given by the coach.