The study of an enemy culture is the key to winning a war. To beat someone, one must understand his or her opponent's brain. If his or her motivations and fears are known, it is much easier to manipulate them. When there is a disconnect between thought processes, enemies could make moves that are unexpected to other cultures.
The study of the enemy's culture and rewards is the future of war, at least partially. Learning how the enemy operates on their own terrain helps us understand how to maneuver around their tactics. It helps undercover representatives blend into foreign culture to prevent terror, for example, and bring criminals to justice.
Yes, studying the enemy's culture and rewards is already a theory in war. If you know your enemy's culture you are better capable of defending against any attack that may originate for this enemy. Not to mention if you know their reward system you are better capable of winning you enemy's heart and mind even in a wartime situation.
No, I do not believe that studying the enemy's culture is the future of war. The reason I say this is because I believe that this is a very old concept and societies and countries have been doing this for centuries. It is a common technique to study the enemies culture to better understand how the enemy may think and therefore make better predictions about how the enemy will think during times of war.