Hiya!
There are many extensive discussions on the causes and outbreak of World War One in our FAQ, which will hopefully be useful! To summarise briefly, World War One was the culmination of years, and in many cases decades, of building tensions and Great Power politics. While it's best not to engage in counterfactuals as to exactly what might have happened had Ferdinand not been assassinated, it's certainly the case that his death was a convenient catalyst for the outbreak of war, rather than a driving force in-of-itself.
If you have any questions, please don't hesitate to ask!
I myself an /u/elos_ have answered questions similar to this before:
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Suffice to say, from December 1912 onwards, the Germans and Austro-Hungarians considered war inevitable, and were awaiting the opportunity to unleash it. Franz Ferdinand's assassination was that opportunity.
While historians generally do not deal with "what ifs", it's generally assumed that even if the murder did not take place, WWI would still have happened.
You see, there were plenty of reasons for the war to become what it was. The rise of German power as a direct threat to British sovereignty, the system of alliances between European powers, Serbian nationalism and terrorism regardless of that particular action, Russian and Ottoman decline creating a power vacuum, etc.
Consider Franz Conrad von Hötzendorf - the Austrian chief of General Staff. The man was convinced there was going to be a war between Serbia and Austro-Hungary even before 1914. He recommended that Austria should wage "preemptive" war against the Serbs 25 times in 1913 alone to reclaim A-H's status as a great power. So the tensions were there. The assassination, as it is said, was merely the spark that lit the powder keg.
Political scientist Richard Ned Lebow argues for the contingency of the First World War. His argument is essentially that there was a "window" of time when war was probable and that absent a crisis with the "right" conditions, this window would have closed by 1916 or 1917. He makes his argument in Explaining War and Peace: Case Studies and Necessary Condition Counterfactuals, edited by political scientists Jack Levy and Gary Goertz. He later went on to write a novel based on the premise. His work is primarily intended as a rebuttal to general theories of world wars.
If you want to read a really interesting book that posits a theory that World War 1 might not have been inevitable, check out Jack Beatty's The Lost History of 1914. While it is a boy rhetorical at times, it is overall an engaging read.
Can I suggest a recent book by Douglas Newton: "The Darkest Days: The Truth Behind Britain's Rush to War, 1914". It focuses on re-examining the account of British involvement in World War One using sources such as Asquith, Grey, and Churchill's personal papers. I've only just started but it's fairly damming in certain areas - the pacifist element in government and the decision to go to war on August 4th being two of the glaring ones.