Although there is a seat at Renault available, and a slim chance of Vettel replacing Valtteri Bottas at Mercedes, the belief amongst many is the 32-year-old German will now retire.
Binotto, though, is not so sure, as he told Sky Italia: "As for Vettel's future, I think he's so passionate about this sport.
"He'll want to get back into it, although he'll have a few things to think about. We're looking at a long-term project.
"I think it was the right thing for him and for us. Only Seb knows what he will do in the future. He's a great driver and he'll make the right choice.
"He spent six years at Ferrari and the team has a special place in his heart. We have a good relationship with him, which isn't to be taken for granted when there's a parting of ways. There's a mutual understanding of the reasoning behind this change."
Ferrari's 'long-term project' means for 2021 Sainz and Leclerc will represent Ferrari's youngest driver pairing in 50 years - Leclerc will be 23 and Sainz 26 going into next season.
Binotto concedes the team has taken "a gamble".
"The world has changed during this time and we have to look at the future of F1 in a different light," added Binotto. "There's a new challenge that we must all embrace and we believe we've singled out the right person to complete our team.
"Carlos Sainz is a young driver and Ferrari haven't had such a young driver pairing in 50 years. It's a gamble for us and we're happy to be taking on this challenge. We want to begin a new cycle.
"It'll be a tough path, but putting faith in youngsters is also geared towards that, not just for the drivers, but also for the mechanics. Sainz is a very nice and intelligent guy.
"He is a real team player and works very hard, so having him alongside Charles will be useful. He's done well over the last five seasons and has almost always reached the finish line, earning his team so many points in the process."
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