Arbitration projections have him likely to get 18.6M for next year. Not many teams want to add that. So yes the cost in trade should be low. You could PROBABLY even get the Cubs to take a smaller contract you don't want, or have them pay part of his salary, to go along with giving them a prospect that they do want. And if he's good next year you probably make him a QO and collect a draft pick.
With all that in mind I think they probably just keep him though