Prediction

Within the next 25 years, a running play will be as rare of a sight in a football game as a forward pass was in the first half of the 20th century. 

It's not going to go away easily, of course.  Coaches, especially in the professional ranks, will cling to the running play out of dedication to traditionalism and muscular militaristic bromides about proper football.  But, given the current state of the rulebook and the skills of modern players, it is going to happen.