I would not bet against the NFL. Still, the very short life of the XFL suggests to me that Americans want to see their minor league football with college branding.
The multi-billions of dollars spent on it begs to differ. Just because they aren't old (are 22 year olds really too young for athletics?) doesn't mean it is a bad product. Many consider it to be a much more exciting game opposed to the 7-3 games the NFL puts out.
I'd rather watch a 49-21 game than a 14-6 snoozefest.
This is really your personal opinion.