Well, athletico bought him at 40mil, performance based can rise to 47 mil, and you can bet a house on it that they will want to make profit if they sell him, as they dont need to.
Its however, great news for us, considering that with such an investment, and the current strikers they have, they'll probably be forced to offload one of them.
I'm not sure wether they will go for it considering the ffp rules, but if they do, marotta should directly pounce on it and offer 20/25 for dzeko.