Red Bull advisor Dr Helmut Marko has confirmed that Honda has not yet decided on its future in Formula 1 beyond 2020.
The Japanese manufacturer returned to the sport in 2015 as an engine supplier for McLaren, however after a tumultuous three-year relationship, the two divorced, leaving Honda to join forces with Toro Rosso for 2018.
This year, Red Bull signed on with Honda, with the two picking up two race wins so far at the hands of Max Verstappen.
However, with the 2021 regulations coming into effect, the futures of a number of teams and manufacturers, including Honda, remains unknown.
"Honda has not yet decided," Marko told motorsport-magazin.com. "I think the decision should be made around the race in Abu Dhabi.
"The regulations are on the table and now you can calculate by how much engine development will become cheaper. There will be restrictions on dyno time and different materials."
Honda's F1 director Toyuharu Tanabe affirms that it has not yet reached its goals in F1, but that Honda's most successful season to date in the turbo hybrid era is giving it encouragement.
"So far we have not achieved our goal," he said. "But winning is already a milestone on our way. This encourages our development department. It shows our attitude and that we continue to fight and improve to reach our goal."