Benitez signed a three-year deal when he succeeded sacked head coach Steve McClaren last month.
But the contract has a break clause for both parties in the event of relegation from the Premier League.
It is expected that Benitez would walk away if the club drops into the Championship, while it has also been assumed that Newcastle would be unwilling to pay his mutli-million pound salary in English football’s second tier.
However, there could be a rethink at United given the studious way he has set about his task behind the scenes in trying circumstances.
Benitez has quickly impressed the players and staff at the second-bottom club, which takes on Swansea City at St James’s Park tomorrow.
The 55-year-old, up to now, has refused to discuss whether he would be willing to stay on in the event of relegation.
Asked last week, he said: “I have confidence we will stay in the Premier League, so I don’t think about the other options.”
Benitez is understood to be attracted by the idea of a long-term project in English football, and he could yet be persuaded to stay and rebuild a club which last won a major trophy in 1969.
Asked if he had any “regrets” about joining the club, Benitez added: “No.
“I want to stay here for a while, so I’m really pleased to have this challenge. For me it is a challenge.
“I am the Newcastle manager and I want to be the Newcastle manager next year.”
Benitez, appointed as manager and not head coach, would want control over transfers should he stay.
And the future of chief scout Graham Carr – who has overseen the club’s incomings and outgoings in recent years – was being questioned by fans long before Benitez’s arrival.
Asked about transfers at his unveiling, Benitez said: “I have to explain why we have to change a little bit, and I think that will be good for everyone.”
Newcastle will undertake a full review of what has been a troubled season, whatever the outcome, at the end of the campaign.