It's still hampered by the fact that we have pretty third-rate players by international standards. The American leagues for gridiron, basketball, and baseball are de facto world championships because the best players in those sports always play here, but in soccer the best club could be English or Spanish or German or Italian, and Americans have a problem with that.
I would say it's a top 4 sport already (displacing hockey) but the top 3 is hard to break into. I suspect it'll displace baseball next.
Not a chance. The NHL is enjoying some of its highest ratings ever.
No, but it's slowly trending upwards. Without looking it up, the top American spectator sports are American football, baseball, basketball, NASCAR racing, hockey, golf, and tennis.
The problem is that the best American athletes look to one of top three American sports - if you look at top NBA and NFL players, many of them seem well-suited to futbol, but it's not where the money/popularity/culture is at in the USA yet. As long as the fast and strong American athletes are looking to become running backs, wide receivers, and point guards instead of midfielders and strikers, the game won't reach the height of popularity. But it'll slowly grow in popularity if the U.S. keeps making decent showings internationally. Being a top 5 American sport by 2030 wouldn't surprise me.
After that, it'd really only take one charismatic, transcendental American player for the sport to really break through - if there was an American Pele, Maradona, George Best type player, it'd go a long ways, just like Tiger Woods did for golf, Joe Namath did for American football, Michael Jordan did for basketball, etc, etc. So I could see the game trending up in the rankings, and then it's all about if it gets the one dominant, charismatic force that people fall in love with who kids want to follow in the player's footsteps.