Since you seem to be unable to tell the difference between an act of war and an act of terrorism, this is probably pointless, but here goes...
Anyone who has studied this period knows that the Black Hand terrorists targeted Archduke Francis Ferdinand precisely *because* he was not an enemy to the Slavic people, but their friend. He was an open advocate for "trialism", of making the southern Slavs equal partners with the Magyars of Hungary and the Germans of Austria. The Black Hand however, were Serbian ultra-nationalists (nationalism being pure poison for a multi-ethnic empire like Austria) who wanted to build a massive "Greater Serbia".
The problem they had with the Archduke is that, if he lived to become Emperor and made the Slavs partners with the Austrians and Hungarians, they might (gasp) be content and not wish to revolt in favor of joining their grand Serbian nation-state. Therefore, by assassinating the Archduke, the Austrians would come down hard on the Slavs and thus drive them into the arms of the Serbian nationalists who were planning war, safe in their knowledge that big brother Russia would come to their aid.
He would have made who co-equal - the Catholic Croats or the Orthodox Slavs co-equals? Try your apologist view of history somewhere else. PS: The Hungarians never loved being part of that crappy empire either.