The 22-year-old has a release clause in his contract — along with team-mate Gary Medel — that he can leave following relegation.
The Bluebirds’ relegation was confirmed following their 3-0 loss to Newcastle on Saturday, although the England defender suggested he would be prepared to play in the Championship next season.
Speaking after the game, he said: ‘I signed a four-year deal here so I’ll be looking to get us back promoted next season.’
However, former Cardiff player Kevin Ratcliffe believes Chilean enforcer Medel is the player most likley to leave the club.
‘He’s captain of his country playing in the World Cup in Brazil this summer,’ Ratcliffe told the Daily Express.
‘Would you want to come back to play in the Championship after that?’.
Meanwhile, Liverpool manager Brendan Rodgers thinks top players from around Europe are keen to join the Anfield revolution because of the thrilling way they have qualified for the Champions League.
Rodgers will be given £60million to spend by the club owners and has been linked with a number of targets, including Ukraine winger Yevhen Konoplyanka, Argentina’s World Cup left-back Marcos Rojo and emerging England talents Luke Shaw and Adam Lallana.