There is a tier in soccer, to gauge where a country is at any given point in time. Not having a professional league for so long, the US has been at a disadvantage. Which makes this point in American soccer history all the more interesting.
1. A professional outdoor league. MLS via 1995. Check.
2. A well established league, including longevity and experienced players. Egh.
3. An expanding league. Check.
4. The sport is growing in popularity with fans and players. Check.
5. The sport takes over baseball in the Big Three. Egh.
6. The sport enters consistent prime time coverage from major TV networks. Egh.
7. The MLS is a quality league. Egh and Check.
8. Cities like Portland and Seattle. Check.
9. Better style of play for the MLS and national team. Egh.
10. The national team has won the World Cup. Egggh.
The MLS has been crucial for the the development of the national team. The MLS has grown substantially, bringing in experienced players here and there, providing guidance to the players. Amazingly, the MLS is expanding. This has been a major concern ever since its inception over twenty years ago. Soccer keeps getting more popular. This evidenced by the expanding MLS and the rush of excitement every World Cup. Possibly, someday soccer will overtake baseball in popularity, pushing baseball to the fourth most popular sport. Until then, soccer will straddle the fourth place position. (World Cup success has everything to do with this trend.) As well, prime time coverage will increase should the USMNT win a World Cup, or, possibly, get to the semi finals. The MLS is always improving, but it's still not high quality on par with teams in Germany, Holland or Italy. The best MLS teams can defeat some of those teams - at their best - but the MLS as a whole is the issue. Coaches like Ruud Gullit, former Ballon d'Or recipient, have tried out the MLS and walked away laughing in frustration. It's a process. Franchises like Portland and Seattle are helping the league get to a consistent prime time level. As Colin Cowherd says, "Soccer is huge." And it will only get better thanks to enthusiastic cities like Portland and Seattle, who sell out every game with mass hysteria. However, as with England, a passionate stadium of spectators doesn't equal a high quality style of play. This, the US still needs to work on. Should the US win the World Cup, everything will be there. That's the big test. And, that's dependent on everything above. With all those things in order, which will take time, a World Cup championship is very realistic.