@Fehérvári And the Ottomans? and i doubt austria would want to add more minorities even if become a third leg in the kingdom, still a well organized A-H is a pretty powerful nation and would change things.
and why would german oppose A-H and viceversa post war? that not make sense.
Karl I/IV actually wanted to add Poland to his realms, this was the so called Austropolish solution, which was accepted even by Germany until 1916, when the idea was completely scrapped, because of the Austrian dependence on Germany.
The German and Hungarian elements did oppose this solution, since it lessens their words, but overall they couldn't do much against it. The Reichsrat can be ignored and the Hungarians can be compensated, with for example Bosnia.
The Ottomans restored the prestige of their country, gained Karst and sime Aegean isles, which I forgot to mention. The Arab revolt was a mere joke, it can be easily crushed once the British are out of the way, the integrity of the country is not threatened what the Ottomans need is some foreign investment, but once they develop their oil production, they will be fine on their own. I don't see them join either side if there's a war, they can make the most profit if they sell oil to both sides.
The German AHP opposition is mostly because to simply make things interesting, however it's not completely unrealistic in the sense, that there could be some friction over Prussian Poland or Greater German unfication attempt, anything is possible. In the end a strong Germany(Prussia) is just another threat to the Habsburg Monarchy.
Sorry for the potential potato quality of my writing, I switched to phone.