Picture 1. Flying World War I. Droping a bomb above enemy lines.
Picture 2. Flying World War II. After the command "Scramble!" allied pilots climb as fast as possible into their airplanes to fight their enemies.
Picture 3. Flying 2010. F16-pilot in his G-suite and on his ejection seat ready for take off.
Only eleven years after human beings learned flying by a human made airplane, World War I (1914-1918) broke out. Aircrafts were at first only used for reconnaissance. Rapidly airplanes were used for primitive bombing as well. The airplane was of no strategic importance. Dogfights were very visible for the troops on the ground but it did not change the outcome of the war in any way.
In World War II (1939-1945) airplanes became of strategic importance. If Germany would have won the Battle of Britain in 1940, by gaining air superiority, the outcome of the war would have been different. The key to the allied success was radar linked to telephone lines on the home bases of the pilots and aircrafts. This made it possible that the allied pilots were in the air just in time - fresh and with enough engine fuel - and at the right place while the germans only had 30 minutes left to do what they had to do above english territory. After half a hour the germans had to fly back to their home bases.
In recent days (2010) airpower has become even more strategic. In the first few hours of a war the outcome of the war is being established. The main target in the first hours is to make the enemy blind: cut command lines and disturb communication between troups. In World War I and II the reliability and the range of the aircraft were the most important constraints. In recent days reliability and range are no longer constraints. In our days the pilot is the constraint. Even with the best training and a G-suite the aircraft is able to make sharper turns than a human being can sustain.
And the future? I guess a mixture between manned and unmanned spacecraft. "Space?" Yep, a craft that can fly in universe' space as well as in the air around planet Earth. A craft that can start, fly and land completely automatically. And (wo)man? We will need them anyway. Human beings will always be able to outsmart human made crafts, weapons and tools in general.