Bayer have just extended their lead at the top of the standings by five points after thumping Bayern Munich 3-0.
Alonso has been linked with the Liverpool job with Jurgen Klopp leaving at the end of the season as well as Juventus and Real Madrid.
When asked if Alonso would stay on as mentor, Rolfes replied: "I'm sure of it," Rolfes said on the Doppelpass football programme. "One thing is the contract, the other is how comfortable he feels.
"He knows we will have a top team next year."
Rolfes also said star midfielder Florian Wirtz, 20, would remain at the club next season.
"Yes, it's the right thing for him. The way he plays, you know he has an environment in which he can develop."
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