The 27-year-old winger is currently on a season-long loan at Ligue 1 side Rennes, and his impressive form has caught the eyes of potential suitors ahead of the summer transfer window.
Khazri has scored nine goals in 18 league games thus far, with three of those coming in his last five appearances.
However, Khazri's asking price could plummet to £4 million should the team be relegated and subsequently become desperate to sell.
While a splendid individual World Cup campaign could still see the winger's stock further rise, escaping the drop will go a long way in allowing the Black Cats to make maximum profit on his sale.
Khazri arrived the Stadium of Light for £ 9million in January 2016, and his paltry return of three Premier League goals in 35 games underlined his struggles with the demands of top-flight football.
Cashing in on him this summer is almost certain, but Sunderland's Football League status by then will determine how much they can get for the Tunisian.