Stoffel Vandoorne's manager has said that keeping the Belgian on the grid is still the "priority" for 2019.
McLaren has announced that its junior driver Lando Norris will be replacing Vandoorne next season.
Alessandro Alunni Bravi, Vandoorne's manager, insists that he remains "confident" about the future.
"It's good that the situation is now official and clear," Alunni Bravi told La Derniere Heure.
Vandoorne is not believed to be under consideration for a Sauber seat, but he is being linked with Toro Rosso, whose own young driver programme is not yet ready with an obvious replacement for Pierre Gasly.
Before McLaren's announcement, Alunni Bravi said he was "100% sure Stoffel will be in F1 in 2019".
"I'm calm and confident about his future as a race driver rather than a reserve driver. That's our priority," he reiterated.
"Stoffel is an excellent driver with two years of experience in a struggling team. He has also learned a lot from Fernando Alonso and was one of his best teammates."
The manager added that they "have a plan A, B and C" if the Sauber and Toro Rosso options do not work out.
