I think Djokovic is a person who likes thinking and implying in the world enough for that, Nadal is different, he's more made of emotions, less of reasonable thinking imo.
I think Djokovic already implies more than what people suspect.
I think Djokovic could be a good champion for the players. He can handle politics very well, since with his success, he has had to deal with media, politician scumbags back home wanting some of his fame to rub off on then, and the whole "Serbian thug" stigma that took a lot of time to brush away.
And I think the ATP itself needs people from countries that are not from the historical or recent tennis core, in terms of development and influence.
Then again, he might start playing golf once he ends his tennis career