USA probably won't win. They're not that strong in soccer as they are in american football, baseball etc, Bosnia hasn't got much of a chance, even though they DID nearly win against France (France being one of the best teams on Earth) in 2011 in the European Cup qualifiers, they were leading 1-0 but in one of the last minutes a penalty shot (which I think was unfair) was given to the French and they scored a goal, making Bosnia second in group and thus eliminated later on.
Enough of my home team though, my opinion is that Spain will win, since they got top notch gameplay. Brazil is very, very good as well. I mean, did you see Neymar's goal against Italy on the Confed. Cup? Amazing! More candidates for the world champ would be Germany (personally, I dislike their team) or maybe Argentina.
Who knows, I bet we're in for a surprise in 2014!