I don't think Xabi Alonso's proposed departure from Bayer Leverkusen at the end of the season is certain as the young Spanish manager is yet to publicly notify everyone about his next move
If Xabi Alonso leaves Bayer Leverkusen, then this will definitely be Bayer Leverkusen's final journey to become champions in the Bundesliga because the chance of winning will not happen a second time with a different coach. Xabi Alonso now knows the strengths and weaknesses of every player that Leverkusen has, so this coach is able to provide the right position for his players to bring victory. It is not certain that a new coach will be able to do what Xabi Alonso did.
This makes no sense. As much as I acknowledge what Alonso has done for the club as a coach, it wasn't him who scored the goals or played the games as a player. If Leverkusen can get a new coach who turns out to be a great match for this club, why do you think they could not play another great season? My assumption is quite different although it comes with the same result as yours. Leverkusen won't be able to repeat a season like this because they are so good that I think only Bayern was as good at this point during a season like a decade ago. Even if Alonso stays there, the next season wouldn't be the same.