The problem for soccer is that everyone gets into the world cup for a month, and then completely forget that it exists the next day. Every world cup people say the same thing, "This world cup is going to start the rise of soccer", and it never happens.
I couldn't disagree more. Back in 1994, the World Cup being held here kind of reawakened my interest in soccer after I quit playing it in middle school (for reference the 94 WC was the summer before my senior year in high school). At the time,though, the interest kind of floundered. MLS just didn't really appeal to me and coverage of the "big" leagues in Europe was non-existent then, unless you had satellite TV. I didn't really learn about the EPL until I saw Eric Cantona kicking a fan during a game on Sportscenter. Yeah a couple friends and I would play FIFA95 or FIFA96 in the dorms, but even for someone thirsty for more soccer there wasn't much around. As such soccer kind of slipped back into obscurity for me. I honestly don't remember a thing about the 1998 World Cup, and for 2002 I was busy in the Army.
In summer 2006 I had a lot of downtime after my second Iraq deployment and rediscovered my interest in the game. England was my adopted team. I watched the US of course, but more out of obligation than passion if I'm being honest. Living in Georgia at the time, I didn't get the impression any around carried about the World Cup, other than an English guy that hung out at the bar across from my apartment.
In August 2006 I visited a friend in Turkey and was amazed to see a Premiership game on live TV. I remember it so distinctly because I'd never seen an EPL match live. Again, the interest was there, but there still wasn't much availability to satisfy it.
A year later, in 2007, Fox Soccer Channel was available in my area and holy crap, live EPL soccer! Much to my surprise once I actually got to watch teams live I'd previously only casually followed over the internet, I was really drawn to Chelsea.
This was around the time I'd say the sport really started to explode. A bar opened in Albany, that aggressively marketed itself as a soccer bar to watch live games and it was a huge success. Watching the USMNT's improbable run of games in the Confederations Cup catapulted international soccer to my favorite sport, yes, that includes college basketball. I watched the CONFED Cup final there with about 150 American fans and about 30 Brazilians. A guy that showed up late told me they couldn't find the bar at first but then
heard a USA chant and found it by sound. All of a sudden the big club teams in Europe were playing exhibition tours in the US. They weren't just filling MLS stadiums, they were selling out NFL stadiums.
2010 - Landon Donovan's goal against Algeria was just more gasoline and already cooking fire.
2011-2012 the USMNT, long used to having to play home games in front of "away" crowds is actually starting to get true home crowds.
2013 - the EPL signs a TV deal with NBC sports.
2014 - We have the kind of outdoor viewing parties I was always jealous of when the showed cities in other countries during the World Cup.
I could go on but realized this post was turning into a novel.
TL;DR Version - As recent as 2006/7 you couldn't watch the Premier League without a satellite dish, now it's on NBC and teams come here to grow their American fan base. Mid-sized cities like Albany/Syracuse have thriving soccer cultures. MLS is quietly and steadily growing. I'm not saying soccer is going to take over or rival the NFL or NBA, but the growth I've seen in its popularity since 1994 is breathtaking.
The World Cup isn't going to start the rise of soccer. The rise already happened.