The Arsenal left-back has been enjoying his best season with the Gunners after overcoming a string of injury set-backs - making 23 starts in this campaign and providing two assists down the flank.
Adam, who made 37 appearances at Anfield and now turns out for Dundee in the Scottish Championship, called him "a top player'".
"Would it surprise me if a Real Madrid, a Man City or any of the clubs in the top echelons come in for him in the summer?" he said.
"I think he's ready now. He's 23, he signed for Arsenal injured and was out for a spell with groin and shoulders problems.
"But he's come back and has matured into a top player. I believe he can go to the next level again. You're starting at £50m too."