Spurs chairman Daniel Levy declared yesterday the midfielder would not be sold.
Walker said: "He'd be a massive loss.
"But, hopefully, Spurs is not a selling club and hopefully they keep hold of him and keep going forward.
Walker, who has had loan spells with Sheffield United, QPR and Aston Villa since moving to White Hart Lane two years ago, added: "He's hard to get the ball off in training and he's good to have around, good to give the ball to.
"He gets you out of trouble and I think he's a fantastic player."