Belgium is a viable democracy and his neighbour don't have any intention of dividing his territory...A-H is not so lucky. Plus i fail to see the Hasburg permit any kind of democraticization or extension of the suffrage in the empire, and more time pass (a decade or two) more this become important and can bring a lot of thing not really pleaseant
France wanted a pierce of Belgium the half century of its history, and as for Belgian democracy, it wasn't like the Flemish had a lot of power there either until after WWI.
1917 is when the new treaty with the Magyar must be signed...and what they want is basically Hungary become de facto independent, yes the A-H army can and will intervene and beat the Hungarians, but this can create a scenario where other powers intervene or even sparks more internal unreast. The other minority even if they don't want leave the empire want a deal similat to the Magyar one and this can erode the Hasburg authority...a big no no for the big wig in Vienna.
What power intervene? Serbia and Romania? I doubt Russia would intervene, as stupid as the support of Serbia was in real history, I think it's unlikely that they would support the Serbians if they're stupid enough to try to invade Austria-Hungary, Italy may be greedy and stupid enough, but if WWI show anything, it was that Austria really didn't need to worry about Italy invading them. Romania is really not a serious threat Transsylvania is nightmare to invade from the Romanian side and Bukovina was heavily fortified. So we may at worst see Austria fight a war with Hungary, while Romania, Serbia and Italy invade, even if Germany decide to stay neutral, I would still put my money on Austria. First they would likely move on the Magyars, which would likely collapse, the Italians would try to invade, which would end as ugly as in WWI, the Serbs would likely have some success, mostly because it would be Hungary they would invade, but the Croats and Bosniaks would likely do quite well against them, the Romanian invasion of Bukovina would fail miserable. After the Magyars hhave been crushed the Austrians would move against the Serbs, which did well in WWI because they were in a defensible position, here they are in the offensive in the flat land of southern Hungary, while another part fought in Bosnia which likely have turned into a earlier version of the Yugoslavian Wars. So I expect the Serbs to be decimated with much of northern Serbia occupied until a peace are reached. At last they would move on Italy, and I think we all know what to expect there.
The A-H empire as Imperial Russia and the Ottoman Empire (but in a lesser extent) where nation who had ended their historical cycle and where at the last rope.
Why, because you say so? In fact if we look at WWI we have several empires collapsing Russia, OE, AH and Germany, but no one say that Germany was on the edge of collapse before the war, but it still collapsed and lost almost all areas with non-German majorities, you could just well argue that all monarchies had ended their historical cycle and where at their last rope, except that UK clearly show this was not the case. I think this is an example of historical determinism, instead of explaning the collapse of empires with the logical and quite obvious reason, that million had died in conflict, the population starved and foreign states push for a break up by supporting seperatist and radicals.