That they thought they could make money off of an airplane patent is proof that they understood that airplanes would be useful in their own right. Had they not done it, somebody else would have, with or without patents; it was inevitable. It might have taken a handful of more years, but it was inevitable.
A crude though reasonable way to estimate how inevitable a development was is to look at the period of time between when the prerequisites for an idea were created, and when the idea itself was created. Some ideas, such as the phonograph (which could have been created at least a few centuries earlier) have a very large span of time between these two things. These ideas could plausibly have been "missed" if circumstances didn't align. Other ideas were devised shortly after their prerequisites. Liquid fuel rockets burning LOX and LH2 were first considered by Tsiolkovsky just two years after hydrogen was first liquefied. Goddard did not know of Tsiolkovsky but that hardly mattered, that idea was inevitable. He, instead of Tsiolkovsky, went through with the idea.
In the case of the Wright brothers, powered controllable airplanes hit the scene quite shortly after suitable engines were feasible. They deserve credit for being the ones that actually did it, but there is really little reason to think that there was ever a risk of a future without planes.
A crude though reasonable way to estimate how inevitable a development was is to look at the period of time between when the prerequisites for an idea were created, and when the idea itself was created. Some ideas, such as the phonograph (which could have been created at least a few centuries earlier) have a very large span of time between these two things. These ideas could plausibly have been "missed" if circumstances didn't align. Other ideas were devised shortly after their prerequisites. Liquid fuel rockets burning LOX and LH2 were first considered by Tsiolkovsky just two years after hydrogen was first liquefied. Goddard did not know of Tsiolkovsky but that hardly mattered, that idea was inevitable. He, instead of Tsiolkovsky, went through with the idea.
In the case of the Wright brothers, powered controllable airplanes hit the scene quite shortly after suitable engines were feasible. They deserve credit for being the ones that actually did it, but there is really little reason to think that there was ever a risk of a future without planes.