What's the PoD here? If it's pre-WW1, it's far, far easier. Post-WW1, I would argue, is impossible. The 1919 collapse was simply far too destructive.
Also, you can't have Austria as a great power without Hungary unless you have something significant to compensate. With a pre-WW1 PoD, avoiding or winning WW1, even better you somehow lower the body count of 1914 (better leadership would do absolute wonders here) is a necessity and not inconceivable.
Eventually, something is going to happen with Hungary, but not what people night expect. While Hungary's economy grew massively after 1867, there were serious issues that were only dealt with in the 1920s when everything collapsed: The countryside is very poor, overcrowded, and the land inefficiently used and dominated by the Magnates. Speaking of the Magnates, there were serious issues within the Hungarian government: It was practically an oligarchy. Only an absolutely tiny portion of the population had suffrage (and I think it was still weighed, even!) and political power was very much in the hands of the Magnates. For example, iOTL during the war, there were serious protests to expand suffrage and at least include veterans, and there was severe resistance in the government. I believe suffrage law was only reformed after the collapse iOTL, and that was after a revolution, several coups, foreign invasions and a very, very crippling treaty.
These issues are, of course, far from insurmountable and there is plenty of potential for reforms if the war is avoided or won. Either way, my point is that unlike what
@Lalli said, Hungary is very unlikely to secede unless Vienna very much messes up. I would argue that Hungary will have a revolution before that can even happen. It was far too advantageous for the Hungarians to stay within the Monarchy. If anything, Vienna will have a good chance at reeling them back in if Hungary finds itself unable to solve their issues (and considering how the Magnates historically dealt with issues, this is easy to believe).
Of course, this is all implying that the gents and ladies in Vienna don't ruin everything and make terrible decisions like trying to centralise everything, insult the Hungarians and generally deal poorly with dissent and minorities. Again, not too hard to believe either.
Anyways, without the war or the army surviving it, Austria[-Hungary] has great potential to recover and resume its impressive 1867-1914 growth or crash and burn like iOTL.