@Aginor, when I lived in Munich in the early '90s, we used to follow the Munich Cowboys. They were a minor team but well attended by enthusiastic fans. Cheerleaders too! Anyway, I happen to know one of the running backs (his older sister was my girlfriend), and he went on to play at Frankfurt in the WFL. So, my opinion is that American football was very popular in Germany, at least when I lived there '89-'04.
I played up through my first year of college, so 11 years from 8 years old until 19. I stopped playing after my freshman year because of having really bad headaches after practice due to impacts (playing linebacker). So much so, that I had a hard time studying at night after practice. Anyway, I elected not to play my sophomore year, and even though at the time I was ashamed at being a "quitter", that might have been a fortunate decision. My gut was that if it makes your head hurt for a couple of hours after practice, even though we had top of the line equipment including helmets, that there was something wrong with either my head or the game.
Where I live in Atlanta, a lot of parents are moving their kids to lacrosse and soccer due to the recent studies on repetitive impacts to the head. I am told that some of the youth football leagues are having trouble finding enough players, while lacrosse and soccer do not have enough team slots, coaches, officials, and fields to play on.
For those fans who think that this is an excuse for litigation, there is always UFC (cage fighting). There is surely enough elbow to cranium contact to satisfy even a caveman. Like it, I hope that football doesn't turn into the blue collar sport that boxing has become.
Not wanting to put a complete downer on this discussion, I am very much encouraged by the new rules in place in the NFL and NCAA which discourage helmet to helmet contact. Let's hope that it is enough. I still very much follow my college team and watch the NFL when there is a compelling game.