Spurs have worked hard to get key men tied down on fresh terms well before their expiration dates approach.
Eriksen is, however, among those yet to commit to a long-term extension and will see his current deal expire in the summer of 2020.
Transfer talk has built around him, as his remains a model of playmaking consistency in the Premier League, and those in north London have been warned that interest from Spain is likely to intensify.
Spurs legend Waddle told Sportingbet: “Eriksen is reaching superstar status and there’s no surprise to read reports of Real Madrid and Barcelona being interested.
“Eriksen’s agents will have asked Tottenham for more money and he will leave if the club don’t give him it.
“Real Madrid and Barcelona would jump at offering him those terms so the ball is in Tottenham’s court.”
Waddle says it is now up to Tottenham chairman Daniel Levy to display his ambition for the club.
If he wants to keep Eriksen then he will need to dig deep, but losing him would create a creative void in a side determined to push themselves into contention for major honours.
“This is where Daniel Levy decides what type of club he wants Tottenham to be and where he wants them to go,” Waddle added.
“It would be a massive statement to give Eriksen a new deal, but would also be a big red flag if they don’t.
“It would be a fantastic move if he signed a new deal, but money will talk loudest.”
Eriksen has already contributed two assists in the Premier League this season, having provided 10 last term to go with a personal best goal return of 14 across all competitions.