Alas, I'm afraid he won't, he should... if nothing to bring some TV audience to the US soccer team... Still MLS is screwing him badly, he should not be in DC United warming a damn bench, he should be in the farm system of Barcelona or something like that. He should be US's Lionel Messi (who by the way is going to be the best player of the world in like 3 years, no doubt about it).
I know he is a money bringer, but he must leave, Donovan has already decided to stay (which I consider a damn stupid move) but Adu should leave, now, as soon as possible, tomorrow actually... THe world Cup would be good for him, even if he does not touch the field ever, the guy should go up there, (the hype that he would be there would make European teams scout the guy) if US is out by the second game (which is a strong possibility, as is a strong possibility that they are already in the second round, you never know with a team like the US but I haven't seen them do well lately, they don't seem like the same team that played awesome in the last WC) they should play Adu, they should give him all the oportunities to get out, I know that MLS is getting money out of him now, but if Adu becomes a star (and the only way he is going to become a worldwide star is if he leaves) then they would have a proven guy outside, proof that their farm sistem works, and people would move in... just a thought.
