Mansell, 41 and the winner of 31 grands prix, has been unavailable for comment over the Christmas period but a source close to the Benetton team confirmed that it was possible he might join the team in 1995 with backing from the French engine suppliers, Renault.
"It is not something that would surprise me, if it happened," said one source close to the team on Saturday.
"You can never say never in this sport and Mansell has made so many comebacks it is always too early to write him off."
A meeting at Williams headquarters at Didcot on Friday finalised Frank Williams' decision to sign Coulthard, 23, but there was no confirmation from the team that any deal had been signed and no announcement to confirm their driver plans for 1995.
A spokeswoman for Williams said the team expected to make their announcement early in the new year.
"We will have nothing to say until the Christmas and new year holidays are over," she said.
Mansell's agent, Sue Membery, said the 1992 world champion, whose Australian Grand Prix win last month may have been his 31st and last, knew nothing of the latest round of speculation.
It is believed, however, that the news may have been delayed until 1995 to ease the pressure on Mansell, who now looks likely to face a clear choice between retirement or hoping he can land the seat alongside Schumacher at Benetton.
Benetton were powered by Ford engines in 1994 when Schumacher claimed the title, but will be using Renault next year.
Renault are admirers of Mansell's racing ability and paid for his return to the Williams team for four races in 1994. They were keen for him to race again for the team in 1995.
Benetton's managing director, Flavio Briatore, is another known admirer of Mansell but he may bow to Schumacher's fears that having two recognised top drivers in the same team could upset their championship assault.
Benetton, however, know they missed out on the constructors' championship last season because of the inconsistency of their second drivers alongside Schumacher.