While Franz Ferdinand had a bad temper and was prone to being rash at times, he did think things through and could famously be calmed instantly by his wife (who just touched his arm and said 'Franzi, Franzi...' when he flew into a rage).
By 1914, Franz Ferdinand had abandoned the triple (or quadruple) monarchy idea and was looking for a federated empire instead. Every part that wanted a parliament might get one, but the foreign, defence and budget policy would be handled by an Imperial parliament in Vienna.
Franz Ferdinand looked to replace von Hötzendorff as supreme commander since they disagreed on war and peace (Franz Ferdinand was part of the peace party and von Hötzendorff part of the war party).
The big question is how Franz Ferdinand handles the Hungarian parliament - he will probably appoint a loyal Prime Minister and force through a suffrage reform (Austria had male suffrage, Hungary only allowed land owners to vote, which together with heavy gerrymandering allowed the Hungarian nobility to control 90% of the positions in the parliament). If the parliament opposes him, he can dissolve it and send in the army. Suffrage has ensured him the support of at least half of the ethnic Hungarians and all their minorities (Serbs in Banat, Romanians in Transylvania, Germans in Siebenburgen and westen Hungary, Slovaks in Slovakia and Croats in Croatia). If the Hungarian parliament resists him, he can just send in the army and crush them.
He'll have the enthusiastic diplomatic and economical support of Germany - Serbia might have support from France and Russia, but not for uniliteral offensive action. The Bosnians were actually quite appreciative of the Austrians at the time - they tried to lynch Gavrilo Princip after the murders OTL. The fact that the Serbs in Bosnia was rather content with Austrial rule (which had brought law and order, potal service, roads and railorads, telegraph and telephone and had caused quite some economic growth) was what the Black Hand feared the most.