Asked if Red Bull was trying to tie Newey down to a five-year deal, team boss Christian Horner said he doubted that was the way to ensure loyalty.
"As with anything – a contract isn't worth the paper it is written on if the individuals aren't comfortable with each other or don't have the desire to be there," said Horner.
"Adrian is very comfortable in the environment at Red Bull. He enjoys working with the team, the team obviously enjoys working with Adrian and I think that will continue for quite some time to come.
"His motivation is still enormously high, he is still hugely competitive, he is still relatively young and he is far from retirement age.
"And I think he will find it hard to find any other challenge that will stimulate him in the way that F1 does."
Talking shop with Adrian Newey
Although Newey has regularly mooted America's Cup yacht racing as a future design interest, Horner believes he is still "engrossed" in Red Bull and F1 at present.
"Adrian has always expressed an interest in America's Cup, since McLaren days," said Horner.
"It is something that at some distant point of the future he may feasibly get involved in, but he enjoys and is engrossed in what he is doing at the moment.
"He is in the halcyon period of his personal career." Yahoo Eurosport