If Erik ten Hag happens to need quite much time to make his system work at Leverkusen, I won't be expectant about a title race next season either.
I wouldn't like to watch a boring Bayern Munich dominance again. Or maybe Kovac's Dortmund would step forward next season? Who knows...
It is also a matter of concern now that their midfielder Jonathan Tah has left the team, so what might be Bayer Leverkusen's attitude after this? I think Bayer Leverkusen has to make some expected contracts such as adding Garnacho and Antonio, maybe it will be very helpful for them.
Midfielder? Jonathan Tah?

I assume you wanted to say defender or CB. Therefore Leverkusen needs to sign a defense player to fill his place. Not a winger like Garnacho or a midfielder...