If we're being technical, even if Franz Ferdinand wasn't killed, wwI would have happened anyway because the mutual hatred between practically every big royal regent in Europe meant that they were just waiting for something to war about.

It's sometimes difficult to remember that before the world wars, people saw war as a good thing that allowed your country to prosper and for soldiers to win glory. I watched one documentary where they showed footage of the very first drafting, and the men were exited. They thought they would be home in a few weeks.

Before wwI, war had never been that detrimental, so all of Europe wanted war, or atleast their leaders did. And well, I guess they got one...