Nico Rosberg has hinted that Mercedes should choose Pascal Wehrlein to replace him.
Valtteri Bottas is expected to move over from Williams to take the world champion's place, but Rosberg thinks that Wehrlein would be worth the "risk".
"Wehrlein is our German hope for the future,"Rosberg told Sky Deutschland. "Bottas is more of a developed driver so certainly Pascal would be slightly more risky, but perhaps he would be even more successful."
Mercedes have reportedly offered Wehrlein to Williams as part of an exchange for Bottas but the British team are expected to recall Felipe Massa who also retired at the end of 2016.