The Spaniard is now searching for his next destination in F1, but his fine form in the opening eight races in 2024 - including a stunning win in Australia - have ensured he will have no shortage of offers to consider.
However, Channel 4 presenter Steve Jones believes the 29-year-old has already delivered a strong hint that he knows where his future lies following an interview with the broadcaster in the principality.
Sainz said: "My priority is to want to remain in F1, but also to allow me to find a medium to long-term project where I feel valued, where I feel I'm being listened [to], where I feel like I can commit to a medium or longer term that is going to be useful for my career."
In response, Jones claimed Sainz's words indicated he is set to sign a contract with Williams.
Speaking live on the broadcast, he said: "Very graceful. Very classy. I expected nothing less. Just after that interview, the rumours started to swirl that Sainz might be joining Williams.
"It's really interesting to hear him talk about a long-term project with a team. In short, he's going to Williams. It's locked in."