Problem was Franz Ferdinand was a progressive who wanted to reform the monarchy and liberalize the country. Princip killed the wrong guy
Franz Ferdinand supposedly wanted to adopt the “Trialist” solution (make the South Slavs a third group on par with the Austrians and the Hungarians in the empire). Whether he would have really tried to implement that if he had come to power is uncertain. For Princip and people like him, that ran against what they wanted for Bosnia—they wanted to get rid of Austro-Hungarian rule altogether.