The team will instead be using in-house engines made by Red Bull Powertrains (in collaboration with Ford), with next year's regulation changes providing a clean break point.
Verstappen's future with the team has been questioned lately though, with Helmut Marko admitting some concerns that he may go elsewhere if the team fail to provide him with a competitive car - with Aston Martin high on the list of potential suitors.
Honda president wants future Verstappen relationship
Watanabe's comments will do little to stall those rumours, admitting that he'd like to work with Verstappen in the future, with the Japanese car manufacturer supplying Aston Martin with power units from 2026.
Watanabe told De Telegraaf: "First of all, we will do everything we can to help him win his fifth world title this year.
"And then our focus will be on our partnership with Aston Martin. But I have to say honestly that I hope that there will be another opportunity for Honda to work with Max Verstappen. I sincerely hope so."
The Dutchman has spoken about his relationship with Honda this season, saying in Suzuka: "Honestly, the relationship that we’ve had with Honda has been amazing.
"I’ve really enjoyed my time with them - how they also work, how professional they are and how dedicated they are. They’ve given me so much.
"Together we’ve won four drivers’ championships and two constructors’ [titles]. It’s been unbelievable and also, of course, something you’ll never forget."