The scenario assumes a repeat of the 1903-1906 crisis, but with the addition that the Croat parties openly lobby the Franz Joseph to weigh in on their side and either grant Croatia a seprate crown or transfer it to the Cisleithanian half of the monarchy (and unite it with Dalmatia and possibly Bosnia and Slovenia to boot).
A popular insurrection backed by the Domobranstvo proves beyond the abillity of civil police to contain and Budapest either seeks to deploy the Honved to restore order or demands that Vienna deploy the KuK to do the same. Either way, FF cannot resist the temptation to stick it to the Magyars (and in any event faces unpalatable alternatives) and ends up backing the Croats and alienating the pro-Habsburg parties in Budapest. Slovaks, Romanians, Banat Serbs and Banat/Burgesland Germans petition FF to back them in seperation from Hungary as ended up doing de-facto for the Croats. The Hungarian parlimant, terrified that FF is set on breaking up Hungary, and possibly egged on by the *entente powers, votes to secede. Russia, France, and Italy see fit to recognize Hungarian secession and enter into negotiations for a millitary alliance with it.
In this scenario, assuming that AH's international situatuation continues to plummet in the pre crisis period (With Italy not renewing the triple alliance in 1917 and King Carol of Rumania and his pro-German policy being buried in 1914), does Germany:
a. Stand by its ally through hell and high water and warn that any attempt by any party to interfere in FFs spanking of Hungary will result in war with Germany?
b. Likewise, but only in regards to Russian interference?
c. Try to get FF to recognize Hungarian independence in return for German gurantee of his rump empire (and Hungarian acccession to a revised Triple Alliance)?
d. Realize AH is a corpse and begin to seek diplomatically palatable ways to carve it up to Germany's best advantage?
If "a", then does Germany desperately go for Schlieffen? Launch a premptive attack on Russia's mobilizing armies while remaining on the defensive in the West? Avoid offensive operations against either major power and instead support AH in crushing Hungary (and Serbia) and repelling a Russian invasion of Galicia? What is the mindset of Germany's Civilian and Millitary leadership (I'm assuming Falkenhyven rather than Moltke would be in charge by 1917) as they contemplate the unpalatable alternatives?
If "d", would Germany seek outright annexation of portions of Cisleithania with all the attendent internal political complications that would entails (Catholic and Czech/Slovene representation in the Reichstag) or seek to transform rump Austria into an outright protectorate/s (Customs union, German control of foreign policy and millitary)? What pretext does it use to take over, how much resistance will FF put up, and what kind of support can Germany expect from ethnic Austrian Germans and/or Habsburg officials and millitary leaders if FF does not reach an accomadation with German takeover? How much of Cisleithania is Russia-France (and Italy) prepared to let Germany swallow and how little would lead Germany to roll the dice choose "a"?