The South Africa international told Kickoff.com: "It is true that I only have two years remaining on my contract.
"It has been a happy two years at the club so far and I am delighted to have played a small part in the success we have achieved in finishing fifth in consecutive seasons and reaching the FA Cup Final.
"But you never know in football what tomorrow will bring. Who knows in one or two years' time where I will be? I am a proud Everton player at present and would welcome it if the club moved to secure my long-term future, but that kind of thing is out of my hands."
Although he would dearly love to remain at Goodison Park, the midfielder expressed an interest in La Liga.
He added: "I enjoyed playing in the Champions League with Ajax [Amsterdam] and have been really pleased when I see how my ex-teammates like Wesley Sneijder and Rafael van der Vaart have gone on to excel in Spain.
"But at this time I can only reiterate that any speculation regarding my future is exactly that."