Yes it's true that Leverkusen has sold some of their players but they are also recruiting before the season starts I believe that they have players that they have pencilled down to buy even though that Leverkusen may not be necessarily as tough as before I will still go for them to challenge Leverkusen for the title race
Not only that, but for next season Leverkusen will also be coached by a different coach than last season, so there will definitely be a difference with their previous performance, but I am not sure that Leverkusen will immediately be strong with the change of coach and changes to some players for next season. Because Munich will still be a fairly serious title challenger for all teams in the Bundesliga because Munich is still coached by the same coach and also still retains more of its old players for next season.