what's the match if not franz's death
While I know of the underlying issues that Franz' death just caused to explode, still possibly nothing. I've only really started examining the context more in depth but it sounds like what basically went down was Franz Joseph had aggressive generals who were eager to sink their teeth into Serbia, and he also pissed off Italy and Russia due to Trieste and the Balkans, respectively. It's especially noteworthy Franz Ferdinand did not like the aggressive posture of the military brass towards Serbia.
Also of note is there were attempts by Britain to join the Triple Alliance but it basically fell apart because (from what I gathered) Germany wanted a defensive alliance, while Britain was more interested in a full alliance it could use to advance its overseas empire. When Germany was a flake on the subject, France was a natural second choice.
A basic thought I had is: if Franz Joseph is out of the picture, Ferdinand's interest in building an overseas empire (and possibly seeing how unhinged Wilhelm was) might have led to some differing alliances. The Dual and Triple Alliances were really just Austria securing neutrality or assistance in the event of war with Russia, rather than a marriage to Germany and Italy, and if Austria is no longer quite as eager to gobble up Serbia and other Balkan states (that is, it has less tension with Russia barring pan-Slavic issues)... Germany starts to look more like a liability. I can see a situation where Austria works its way into the good graces of France or Britain as part of a strategy to establish a colonial empire, and Germany is basically left standing alone barring maybe an alliance with Italy against France and Austria. I wager Britain is more likely, because France's alliance with Russia would probably complicate Franco-Austrian relations even if Austria relaxes its Balkan ambitions.
So you'd have France-Russia, Germany-Italy, and Britain-Austria.
Oh, and for extra funsies, you have Franz' federalization plan which would quite possibly cause some sort of uprising in Hungary.