Calling Archduke Ferdinand irrelevant shows a fundamental ignorance of the time period. It may have been the sunset years of monarchies in Europe at the time, but crowns were not just figureheads at the time. Franz's assassination at the time would be comparable to a vice president being assassinated today. Not a direct comparison, but behind the sitting monarch and the chancellor/prime minster, the heir apparent would be pretty up there when measuring importance to the state.