There's no doubt that while a huge portion of the country is clueless about the WC and football, every tournament gets more attention and a bigger audience, which is encouraging. Especially in the metropolitan areas, there are loads of bars and restaurants showing matches, far more than say 2002 or even 2006.
as someone said, the best part is that soccer is incredibly popular with children and highschool kids, so each generation brings more football fans into the US populace