It is believed the north Londoners will slap a £63m price tag on their prized asset.
Walsh told the Sunday Mirror: “Of course they should keep him, but they could also cash in by buying three world-class players for that amount of money.
“Gareth has three years left on his contract, so the club can say: ‘You’re not going anywhere. We are going to keep you.’ But they also have to think that he may have to go, depending on their financial situation.
“Obviously getting into the top four will help.
“Others have gone before him so you can’t rule it out.
“I don’t think it’s the end of the world because they could really strengthen the side with three fantastic new players.”