The 24-year-old has already signed a pre-contract agreement with the English club, but relegation from the top division would scupper the deal, according to Louis Laros.
He told A Bola: "There is a special clause in the deal accepted by all parties that stipulates if Norwich leave the Premier League then the future of Ricky van Wolfswinkel will be open again.
"That is the reality, but we are confident in the ability of the English club to remain in the top division.
"For now Ricky is only thinking about Sporting and helping them to get results. At the end of the season he will start to focus on Norwich."
Norwich currently sit 14th in the Premier League table, four points from safety.