I've been following Arsenal in the EPL for about 15 years. I have many friends from North London, so I kind of inherited their team. It used to be unbelievably difficult to follow and I used to watch dodgy streams online. NBC Sports now has some of the best EPL coverage in the world. I can watch EVERY game on TV at home. We actually have better coverage than they do in the UK, much to the chagrin of my mates... I actually never miss a game. I can even watch on my phone if I can't be at home.
The World Cup is amazing, but there is nothing like following a club team. I was able to go the the WC in the US in 94 and France in 98. The sport is growing everyday. The MLS is kind of a joke league to me, but when people from the US watch REAL football, they get it...
I wouldn't be surprised if Soccer/football leap-frogged one of the top 3 sports in the next generation. The growing latino population, along with the growth among native sports fans - not to mention it's growth among kids, could make it one of our biggest sports in 20 years.
I also want to mention, as the sport becomes more popular, more kids will want to play soccer instead of the top 3 sports. In a generation or 2 we could be contenders for the World Cup. Imagine the best strong safety or point guard playing soccer instead of American football, or basketball. We'd kill it!