However, Sainz's impressive form has attracted interest from several teams. Audi, a powerhouse brand entering the grid soon, is reportedly keen on the Spaniard to bolster their lineup.
A potential switch to Mercedes could also be on the cards, with Sainz potentially filling the void left by Hamilton's departure to Ferrari.
Even Red Bull, where Sergio Perez's contract expires next year, has been floated as a possibility, though the Mexican driver's strong showing this season complicates matters.
Helmut Marko recently offered some intriguing insights into Sainz's situation with Sky Germany after FP1 at the Chinese GP.
Asked what the chances are for Red Bull to persuade Sainz to join the Milton Keynes squad, the Austrian said: "As long as Sergio does a good job like he's doing at the moment, it's not an issue at all.
"There is a certain time pressure. If we are correctly informed, then Audi are putting pressure on Sainz and they would like an answer as soon as possible. We're certainly not ready to make a decision yet."
Sergio Perez has finished second behind his team-mate Max Verstappen in three of the first four races of the season and is currently sitting second in the drivers' standings.
While not explicitly confirming Red Bull's interest in Sainz, Marko left the door open. Asked whether there is a possibility, Marko said: "Again, Sergio Perez is currently having his best season with us since he joined Red Bull. There is actually no reason but you always have to ask around, orientate yourself and look into the future.
"We know Sainz. He started his career with us at Toro Rosso together with Max. But as I said, nothing is concrete at all."