More about luck, balance of power and the art of postpone a real solution to the problem till it's too late; a late victory in WWI mean that no pre-war problem has been really resolved and we have just added the post-war problem aka massive amount of
death, widespread phisical and economic destruction, the total loss of legitimancy of the old enstablishment (and that were problem that everyone, even the victors, had suffered once the gun fall silent).
The army had remained together during the fight against an external enemy and with an very big help from Germany; in peace time things will be different as many will want changes on how things are run in the Empire; a thing that people in Wien and Budapest really don't want.
We are talking about the biggest conflict know to man till that moment, a bloodbath that was not even immaginable half a decade before...it put a pressure on the nation-system like nothing before; look what happend to Russia or Italy after the war just to make some example and even the people in Wien know that a prolonged war will have mean the end of Austria-Hungary, for this reason had done that half assed attempt to peace negotiation know as the Sistus Affair
All the old powers faced that by end of WWI, and communists globally were convinced that the end/beginning was near. By 1914 A-H was a rapidly industrialising "nation", growth rate only superseded by Russia. That will of course continue after the war but will also mean that communists IMHO are a bigger threat than separatists. Not that various separatist tendencies couldn't be important, it was for a reason that the Balkans was called "the powder keg of Europe", but the Habsburg fraction will have at least as many options in this game as any other - and not at least important - in a CP victory TL A-H can count on heavy support from Germany in fighting any threats to the established order and at least for some time the losers of WWI will not be able to intervene, and if the problem is communist they will happily watch the German Army and KuK slaughter the Reds.
I could however very well see Germany turn socialdemocratic not too long after WWI. That will not help the communists anywhere, and not necessarily the separatists, but nobody says that a state centered around the Habsburg realm will have a crowned Monarch at its top. In Scandinavia, UK and Netherlands the socialdemocrats found a compromise with the Monarchs and I certainly think that would also be possible in a CP victory Germany - and the fate of A-H in this case probably much rests on what happens in Germany. In the last half of 19th century Austria turned from the leading continental power in Europe to a junior partner of Germany.
But still, I think our contemporary view of Austria(-Hungary) often is very much biased by no one really having been there to defend their case for the last 100 years and in the 100 years preceeding that, the ones trying to effectively lost the battle over the German soul to zealous Prussians - who's view on big and small was the basis of later English speaking historians.
Many years ago I did some quite comprehensive studies of the 1813 Autumn campaign (for wargaming purposes) and got access to a number of early 19th century accounts of said campaign - ie. written before the Prussians had taken over the academic German speaking world. I was stunned over how differently these sources described the Austrian contribution in big and small events - I certainly couldn't recognise the view usually seen in Prussian/English accounts/sources about a lacklustre effort and ill-clad and ill-trained peasants not understanding what their officers said.
I of course realise that a lot happened in the world between 1813 and 1918, but I'll stick to my basic claim of contemporary views on Austria-(Hungary) usually underestimating the cohesiveness of the Empire by early 20th century.