Say that in 1848, the Hungarians win the Revolution, I cant really know how (Not good with Austrian/Hungarian history)
In my view (which is by no means the only one), the Hungarians never had a fair chance of it. The Croats were keeping their hands full, the Serbs and Romanians were a nuisance, and they had no real infrastructure backing them up; they lasted as long as they did because the Austrian army proper was largely in Italy.
Taking that interpretation, Hungarian independence requires foreign involvement. With a PoD a bit earlier to adjust how things unfold in France, France or Britain could get entangled on the side of the Italians (they were both pretty close, at times, in OTL), and the Austrians end up with too much on their plates.
It's not easy, in my opinion, but let's leave that and carry on with the hypothetical. I'm going to assume that Hungarian victory necessarilly implies Italian victory.
Would Austria be slowly balkanized by the Czechs, Galicians, Croats, Poles, because it lost one of its major territories or could've it ride out by keeping them and survive without Hungary (Which the Austrian Empire looks honestly weird without the Hungarians...)
To go quickly down the list...
The Czechsweren't ready to try for a state yet, because they had yet to populate Bohemia and Moravia's cities. The mass rural-urban migration of industrialisation was certainly underweigh, but many cities remained German dominated in population and political terms. The Czech intelligentsia were still in the process of moving from a literary to a political sphere. The Czech movement had support, and demands, alright, but there simply weren't enough Czech-speaking, Czech-feeling lower-middle-class types to build a state out of.
Croats would be angling for more autonomy and unity for their provinces - Jelacic was a patriot, in his way, and the Croats were very bitter about getting as reward what the Magyars had for punishment under neo-absolutism. Could a beaten Austria adopt the same strategy? Unlikely. The loss of Lombardy brought about the end of neo-absolutism OTL. So a move towards Croat autonomy - but Magyar irredentism, however unreasonable, is a strong incentive to stick by Vienna.
("Unreasonable" - I feel I should make clear that any Hungarian attempt to press claims on rump-Austria, though not impossible, would mean a neat Austrian victory unless Hungary was merely the agent of some much more powerfuul country.)
Galicia was already, after 1846 and the Slaughter, coming to be dominated intellectually by the alliance of "Stanczyks" and "Podolians", Polish nobles and intellectuals who ridiculed the idea of armed revolt and advocated cultural and political development in Galicia. Bizarre as it may look, Galicia would
want to remain under Hapsburg rule, the only alternative being Russia. But that would probably mean a very autonomous Galicia (and Galicia got pretty damn autonomous by the 1870s IOTL), and the more autonomous it gets, the nearer you get where the Russians decide it's Poland in disguise and invade the place.
...Which would have very interesting consequences for the Ukrainians, whom I assume you mean by the "Galicians". Their (tiny) literate class of mid-ranking Greek Catholic clergy and defiantly unPolonised landowners were hypnotised by the appeal of Russian culture at the time, whereas the masses were illiterate. Modern Ukrainian nationalism basically happened when the emerging Ukrainian middle classes of 1880s Galicia started reading the works of exiled "Little Russians" and evangelising them to the masses through Prosvita, and their increasing influence on the Greek Catholic church. What would happen if the Russians were right there - persecuting those exiled poets, promoting Russophilia, and ruthlessly championing the Moscow Patriarchate - is an interesting subject all to itself, but off topic. The simple answer to the actual question is that the Ukrainians didn't yet have enough "national existence" to really matter.
My conclusion: yes, Austria-Bohemia-Croatia can hold together, for want of anything better, but it's easier if Galicia is swallowed by Russia to simplify that issue.
Austria would still be strong enough to hold itself together. They may even come out stronger than in our timeline. With less nationalities to suppress they'd be able to spend more capital on increasing it's influence outside of its borders, specifically with the smaller German states to the north.
The end result may be a much later German unification.
What "capital" did Austria spend in repressing the nationalities? Austria actually more-or-less stopped actively persecuting anybody on national rather than political grounds after the end of neo-absolutism. The Hungarians, of course, enthusiastically restarted it after Ausgleich, but by the very terms of the question Transylvania and Slovakia are well out of it.
Austria was too powerful to be included into Germany as it was formed in our timeline. Prussia wanted to dominate the nation and a large Catholic state was a threat to that.
Dubious, in my opinion. "Prussia" - that is, a particular section of Prussian opinion that was in and out of favour at differant times, but such is always the way - wanted to dominate north of the Main. In the 1850s, this was usually thought to mean getting command of the Confederal forts and forces there, not political control over other states, Catholic or otherwise. Most advocates of this policy were suspicious of German nationalism at the time.
Yes, Bavaria was Catholic and included into the empire but there weren't enough of them to make Protestants anything but an overwhelming majority.
In any case, it's wrong to assume that our Germany - a fairly tight federation ledd by a massive Prussia - is the only possible one. Changing 1848 completely changes the game for the following decades. Prussia, for all we know, could get flattened at some point, and leave the leadership of a loosely united Germany to rump-Austria.
