I think it will be years until the rest of the world caught up to the US in talent in [American] football. That is if they start playing it.
And when I say years, I mean if and when they start playing it... and I mean when you see fathers and sons throwing the ball around in the yard instead of kicking it.... then add another generation or two.
Hockey, basketball, and baseball have been worldwide games for years. Hockey migrated into the US. Baseball started here, and was here for 150+ years before international players started being major contributors. Basketball started here and it was about 80 years before it was worldwide enough to commonly see international players in the league.
The NFL isn't going to see a lot of international players coming into the league overnight.