But I think theyll get them pretty quickly, because as said I dont think Hungary will behave any different to how it behaved IOTL inside A-H.
That's probably true, but on the other hand, as the Magyars only form half the population of Hungary proper, let alone Croatia, they'll need
someone to help them maintain dominance - and in this period Transylvania is still a separate unit.
But what forces do the Croats have? Italy has the Piedmontese forces, and probably more as soon as Central Italy joins (which in this scenario might well happen already now). If the Italians simply land forces in Dalmatia, can the Croatians stop them? Especially given the Hungarian threat in their flank? And does after all that chaos Austria still have enough forces to stop the Italians should they go for Tyrol and Istria/Littoral?
But there's no Italy in 1848, and none of the Italian states have a fleet on the Adriatic.
This German Union (which eventually will probably be named Gemran Empire for obvious propagandistic reasons) will indeed be much like the OTL German Empire, united and led by Prussia. However, what else can the Prussians do? The Habsburgs already will have to accept submission under them inside Germany and consequently also the loss of their Imperial title. And probably lose Galicia now, too. They can be pushed only so far, I think, and I dont think Prussia would want an outright war of conquest. Especially not with the other Great Powers watching.
I guess what I'm saying is is that I'm not sure anyone in Austria will have any use for the Hapsburgs in this scenario.
As for them, bribing off Russia with Galicia seems indeed like a prudent diplomatic move. Croatia OTOH... that depends on what the Hungarians and Italians might try and wether they have success. The Croatians themselves are very much Habsburg loyalist. A souvereign kingdom in personal union with a member kingdom of the German Empire would be a weird construction, but a Croatia inside the German Empire would be even weirder, and that would make the Habsburg parts of it even larger...
The Croatians were largely Hapsburg loyalist because they needed them to maintain their position vs Hungary. In this scenario the sole reason for their loyalty is removed. Likewise, the Hungarians were largely loyal to the Hapsburgs because they needed the empire to keep their hold over Croatia, not to mention their other minorities. Does a non-Hapsburg Hungary really have the power to hold all of their non-Magyar territory? I tend to think they can, in the case of the Slovaks and Rumanians, but Croatia, unlike the rest, is made up of and organized stand-alone political units.
Croatia as part of the German Empire seems both unlikely and undesirable from the German standpoint (Trieste and Pola are quite enough!), which is why I was thinking the kingdom would just become independent, probably with some Western monarch assigned as king.
Although in 1848 it was actually not unified yet - it's still Croatia, and Slavonia, and there was still that weird military frontier thing. I guess since legally they are part of the Crown of St. Stephen, they'd go to Hungary, and probably be a big problem until they eventually achieve independence. I would imagine violent revolt would begin immediately upon the separation of Hungary from Austria.
Yes, I dont think any power outside the Ottomans will care much that the Bukovina used to be Moldovian less than 100 years ago. And while Russia doesnt need such a small spot of land, if the intent is to bribe the Tsar then giving that land to an Ottoman vasall might be counter-productive.
Actually I don't think the Ottomans would give a fig that Bukovina used to be part of Moldavia - only Moldavia & Wallachia would. The Ottomans would probably nervously eye it as a change to the status quo that could only cause them problems. I can see the powers demanding it be given to Moldavia as "compensation" (counterbalance to Russian acquisition of Galicia) - that happened quite often to the Ottoman vassals, albeit usually at the expense of the Ottomans - although the chunk of Bessarabia given to Moldavia after the Crimean War is an exception.