Well, on the books there is only remaining 3.59M from his amortization, along one year salary. That is assuming Transfermarket numbers are to be trusted.
so, anything more than that is a profit for us. And likely his salary is way more than that so even if he leaves for free it is still a win for Barca. He should be an option there for depth.
Heck, if Atletico shows no interest I would seek a mutual agreement of contract termination with him. We don't pay him remaining salary and he can go and negotiate a new deal wherever he wants to play.