Nico Rosberg has said that he is surprised Fernando Alonso is keeping up his "motivation" amid the McLaren-Honda crisis.
On Wednesday, the British team announced that Alonso's 2017 teammate, Belgian rookie Stoffel Vandoorne, is staying next year.
Meanwhile, two-time champion Alonso's decision about what to do next year is less clear.
That is especially true given the fact that Mercedes and Red Bull are expected to field unchanged drivers next year, and Ferrari have just re-signed Kimi Raikkonen.
"Formula 1 is still my priority, it's my life, and winning the world championship is what I'm hoping," Alonso told CNN.
"If I don't see any project that will allow me to fight for the win I will look outside F1 - but that's [a decision for] November-December. I will try all the possibilities before that."
Alonso has suffered through McLaren-Honda's performance and reliability crisis since 2015, and now-retired reigning world champion Rosberg doubts that he could do the same.
"For me, after those years of fighting for the championship, I couldn't do that," the German told Auto Bild.
"I would lack motivation."
The championship resumes this weekend with the Belgian Grand Prix following the summer break.