Please read what I said--I believe that the popularity growth of football in other nations will be greater than the popularity growth of futbol in the U.S. I don't see how your comment applies to that assertion.
My apologies, I did read it incorrectly, but I will still disagree with you on the point you are talking about.
Several countries have their own big time sport that is only really popular in a few countries. Canada and ourselves are really the only countries with pro football leagues. Baseball stays within North America and Japan. Hurling is massively popular in Ireland, but nowhere else. Cricket is huge in the UK, India, Australia, and other former British Empire nations. Rugby is very popular in several other European countries and South Africa. Australia also has its own "Aussie Rules" Football, which I can't even begin to grasp.
The point I'm making is that many nations don't really see the appeal to football, much like we don't see the appeal to other sports like i mentioned above. Soccer is a international phenomenon with almost every nation in the world having a men's national team. Soccer in the US already has a pretty firm foothold with a passionate fan base that statistical data will show that it has steadily gained support over the past decade, whereas football isn't on the radar with any countries outside North America.
To make an incredibly long story short, there simply is not enough intrest from countries outside the US to even think about beginning a pro league in any other country outside of North America, which is a crucial step for a sport to grow in popularity. While I don't think that soccer is going to surpass football, baseball, basketball, or hockey, it will definitely continue to steadily grow in the future.