any intervention in A-H will not be a single event but a long and tiring work as that nation without external help will simple disintegrate.
Why should it be "long and tiring"?
The Czechs and Slovenes know perfectly well that if A-H dissolves they'll find themselves annexed to the Reich, so for them the only choice is between indirect German rule (under the Habsburgs) and direct German rule. Independence is not on offer.
The Hungarians know that if they bolt from the Dual Monarchy they'll be under Germany's thumb just as much as A-H was before - probably more so as the disparity in size is far greater - and may get carved up.
The Croats know the same, and also that if they are strong enough to break with A-H they don't really need to do it, as they are also strong enough to secure a bigger measure of self-government within it - a safer option than becoming a mini-state precariously wedged in between Germany, Italy and Hungary.
These things being so, enough are likely to stay loyal to enable A-H to put down any scattered revolts with only a modest amount of German help - if indeed any is needed at all.