The US will never be #1 for several reasons!
for a sport to be successful in a country you need inner city and or poor kids playing that sport. They have to view that sport as a means of escaping generational poverty. Go to any country where soccer is #1 and will see that poor kids embrace it like a religion. Basketball and Football are viewed that way in the US. Same as Hockey in Canada.
Go to Latin America and ask about their love for baseball then look at the roster of any MLB team.
Once Mexico recaptures the South West of America soccer will become our national past time...just look at the population calculations, probably in 20 years.