X's and O's are overrated. A team could win using the single wing offense if properly executed with good talent. It's innovation to adapt to what defenses are used to seeing on a weekly basis that drives different offensive philosophies. I would argue Auburn this past year would be just as successful running the ball with any style offense.
I think the spread will become less popular to use as defenses become more and more accustomed to defending it. Just like happened with the veer, wishbone, run-n-shoot, etc. However until the rules allow pass defense the freedom they used to have, the passing game will continue to become more prevalent.