Sebastian Vettel is not committing to F1 beyond 2020.
The Ferrari driver says there is too much uncertainty about what the regulations will look like under the new Concorde Agreement.
"I'm certain I really want to drive this year and next year, then I don't know what happens to the regulations," Vettel, a quadruple world champion, told the Sunday Times.
"I certainly can't sit here and say no (I won't quit) just for the sake of being in formula one," he insisted.
Ferrari is also playing hardball regarding 2021, amid rumours Liberty Media wants to drastically cut the amount of extra funding that is pushed to Maranello.
There are now widespread reports that the top teams are giving themselves until December, rather than the end of June, to sign deals with the F1 owner.
"I think it's important to negotiate the right deal, and we should take the time to do it," said Ferrari team boss Mattia Binotto.
Vettel says his big issue is that F1 is steadily becoming "more a show and a business than a sport".
"A lot of the values that used to be around, they are only partly around (now)," he said.
"You can say the same probably for other sports, but maybe in other sports it doesn't filter down as much to the actual athlete as much as it does here."
