[MPJackal]

"If the Archduke had never been assassinated, we would be living in a very different world today, one in which Fascism and Nazism and Communism would be mere words in a dictionary"

Possibly, but doubtful. That may have been the final straw but the writing was already on the wall. Obviously it is impossible to predict what would have been different, but I think the world was on course for the war, Franz just showed them the shortcut.

"The Balkan Peninsula or the "Powder Keg of Europe" because tensions there threatened to ignite a major war. Rivalry for control of the Balkans added to the tensions that erupted into World War 1."

"The assassination of Archduke Francis Ferdinand triggered World War 1. But the war had its origins in developments of the 1800's. The main causes of World War 1 were:

The rise in nationalism
Build-up of military might
System of military alliances"

[Lx]

The rise in nationalism Build-up of military might System of military alliances

You forgot the most important reason, it was all GW Bush's fault.