Which could just start a World War since Germany was looking for any excuse to cut Russia down to size, Russia wanted the Balkans and all the Slavs, France wants back Alsace and Lorraine, Italy wants the whole Adriatic, and the Ottomans still need a sugar daddy who is anyone but Russia. FF surviving changing none of the root causes of the First World War, only delays it while everyone tries to make up an excuse for it.Stenz is correct, but sometimes a new debate can produce new insights. With that in mind I'll elaborate what I think would happen. Franz Ferdinand combined a plan to federalize the empire and give its minorities more autonomy with a hatred of anything Hungarian. The Hungarians will refuse to go along with any plans to alter the original Ausgleich agreement apart from some cosmetic changes because they don't want to lose power by sharing it. As it were, the renegotiations of the Ausgleich that took place every ten years always produced constitutional crises, but Franz Joseph held the country together every time.
Given his dislike of the Hungarians, Franz Ferdinand will push through his plans regardless of Hungarian objections. Two things can happen: 1) the Hungarians break away, producing a civil war in Central Europe that leads to the partition of the empire, or 2) the empire sticks together because the Hungarians realize they're better off as part of a great power than as a middle power on its own given the ambitions of its Serbian and Romanian neighbours and therefore grudgingly accept a compromise (possibly also because Germany gives the Hungarians a stern look).
Which could just start a World War since Germany was looking for any excuse to cut Russia down to size, Russia wanted the Balkans and all the Slavs, France wants back Alsace and Lorraine, Italy wants the whole Adriatic, and the Ottomans still need a sugar daddy who is anyone but Russia. FF surviving changing none of the root causes of the First World War, only delays it while everyone tries to make up an excuse for it.
Hungarians threaten secession, Austrians tell them don't do it, Russians tell them to do it, Germans say don't, French say do, Italians say do, British look on in concern as the whole continental balance of power flops dead to the floor. That'd be an interesting scenario, I think at least. Might be too much of a stomp for the Russian side though (no Carpathian defenses means Austria's going to be in a world of hurt).
...trialism ... actually took place towards end of the war.
The biggest misconceptions about Austria Hungary on this site are probably
1. It was politically re negotiated every ten years
Reality=it wasn't, certain economic issues were settled every ten years
2. united states of greater Austria was not just possible (very very difficult to do in my opinion) but was actually the most likely outcome if franz Ferdinand survived.
Reality=trialism and greater voting rights to Hungarian working class is likely, trialism as a whole was far more [popular than federalism and actually took place towards end of the war.
3. The national minorities including Hungarians were eager to bring down the empire and mutiny/civilwar/ww1 would take place had the Hapsburgs pissed them off in some way.
Reality= The most antagonistic groups in early 20th century Austria-hungary were ethnic serbs and Hungarian nobles, most were content with the situation and loyal to the Hapsburgs the largest opposition was seen in riots and little more. THe Hungarians were very unlikely to try and declare independence if franz reduced their power, for example of this see plan U in 1905-6 where the honved declared martial law and disbanded the parliament, staying loyal to a monarchy they assumed was reducing power of Hungarian nobility and granting further rights to minorities.
The idea that any attempt to reform the empire would result in civil war is pretty annoying.