The Kenyan midfielder was denied an exit from St Mary's over the summer, with Tottenham Hotspur keen on securing his services.
"We know he has two more years on his contract, and maybe in the next few months the club will have a good time to talk to Victor about that," said Koeman, in quotes published by ITV Sport.
"And it's all about the player: we like to keep the player for more years, but it's up to the player."
His transfer request was denied, as reported by the Daily Mirror, with Southampton adamant that no more of their stars would be sold following the departures of Morgan Schneiderlin and Nathaniel Clyne, and the loss of Toby Alderweireld to Tottenham.
Wanyama is now something of a veteran figure at St Mary’s, as one of a handful of players remaining after two successive summers of major departures.
How much longer he remains is another issue altogether, and a fresh approach from Spurs in January would unsettle the midfield powerhouse even further.
Any imminent contract discussions are likely to involve a buyout clause in some capacity and despite the club’s determined efforts, Wanyama’s exit seems as case of when not if it happens.