But... why?
The Hungarians were basically, if not completely the key to Austria's survival during the Austrian Succession War. Without them, Maria Theresia would never have been able to succeed the Archduchy and her husband wouldn't have become HREmperor. Likely, an Austrian victory over the Prussians in the SYW is dependent on Russia not abandoning the alliance, but Austria wouldn't have been able to wage an offensive war in the first place without Hungarian military and economic help. The loyalty of the Hungarians (and I use 'Hungarian' in the non-ethnic, Kingdom-wide sense and not the ethnic Magyar sense) was incredibly important and I don't see why the Habsburgs would abandon them so easily despite these massive and, in my opinion, untenable conquests.
As for internal struggles with Hungary: Historically, the revolts in Hungarian territory in the 18th was due to the fuzziness caused by the Reconquest when it came to autonomy and noble privileges+rights (esp. with the end of Transylvania as an 'independent' state), as well as the Catholic vs. Protestant tensions and the generally-poor governance in reconquered territory (after all, the switchover from Ottoman to Austrian administrations was far from an easy task). In other words, they were more akin to civil wars (see Kuruc vs. Labanc) with a mix of a Noblemen's and religious revolt. Meanwhile, the 1848 Revolution was also more like a civil war (as revolutions tend to be) and was so much more complicated than a mere anti-Austrian revolt.
If the Hapsburgs had abolished the rights Hungarian nobility and implemented universal suffrage, then the Magyarization that happened in OTL would be butterflied away. I think the Hapsburgs would have wanted to avoid doing that but if the nobility forces their hand by launching a rebellion, anything can happen.
Now the empire may end up looking like a version of the Ottoman empire with one ethnic group have supremacy over other ethnic groups. However nationalism would still become a problem and we might still see something like the Dual Monarchy as a way to preserve the empire against the tide of nationalism. Instead of the Austrians sharing power with the Hungarians, it would be the Slavs in the empire. ALL of the Slavs. Maybe in this timeline Austroslavism would have a chance of preserving the empire.
https://en.wikipedia.org/wiki/Austro-Slavism
You are aware that the Austrian half of Austria-Hungary adopted universal male suffrage in 1906, right? You'll need butterflies to apply it not only earlier, but throughout the Empire. Remember that if you want to weaken the Hungarian nobility, then the nobilities of the other crownlands (esp. Austria proper) need to be weaken as well.
Austroslavism was just as likely, if not less likely, to succeed in the long term as Dualism with the Magyars. First of all, the Slavs of the Empire were far from united. After all, there's a reason why the Austrians negotiated with the Hungarians only: They make a stronger power bloc on their own than the Czechs, Poles, or Southern Slavs on their own.
In my opinion, the Austrians should've negotiated a federal model by bringing the Hungarian and Austroslavic liberals together instead of pushing them apart. Of course, they didn't since the Austrians wanted to limit decentralisation and keep Vienna relatively strong. Hindsight, though, and I'm straying away from OP's question.
An Austria with Silesia and Bavaria is an Austria that dominates Germany, more so when they have Belgium still rather than Venetia-Lombardy, this means they don't need to bend over to the demands of the minorities.
This, in my opinion, is unlikely (except the part about Venetia, that is definitely something to consider). I seriously doubt that the conquered Bavarians and the other German states are going to make it easy for the Austrians to maintain what, like I said earlier, was untenable. I believe Vienna would be even more dependent on the minorities in order to keep the Bavarians subjugated and any resurgent Prussia/Northern Germany at bay.
In such a situation, how plausible is it that Austria wins out in the internal struggles with Hungary? During a Hungarian revolt, could they have broken the power of the Hungarian Kingdom, dividing it up into smaller principalities? Could they have flooded it with more German settlers to the major cities, eventually leading to German becoming the primary language?
Chances of victory: Very good for the Austrians unless external forces take advantage, which puts them at a massive disadvantage.
Could they have broken the power of the Nobility? No. Not before the Austrian nobility herself is weakened as well. Destroying the Hungarian nobility would be tantamount to Radicalism. You need a much different Austria for that (which might even butterfly a Hungarian revolution away).
Could they have partitioned Hungary? They did iOTL and it failed miserably.
After 1848, Hungary was divided, as the map shows, into five Military district while Transylvania, Croatia, Slavonia and the Military Frontier had their autonomy restored (directly under Vienna this time) with Vojvodina and the Banat formed as a new one. It failed miserably as the Hungarians, for the most part, refused to cooperate. Without much support with the Magyars, the Military occupation was untenable in the long run, weakening the Empire as a whole and partly allowed Prussia to crush her in 1866.
Could they have flooded the cities with settlers: I really don't think so. If I'm not mistaken, there was no real force to drive Germans to migrate en-masse into Hungary. After all, it was deemed better to just cross the Atlantic instead and I doubt you can turn Hungary into some kind of Land of Opportunity like you can with the New World. Especially not in the 19th century. The last big wave of German migration into the region happened directly after the Reconquest, but the social and political circumstances of the time made it possible.
I think the best you can hope for is for German to become a widespread second-language throughout the Empire, including Hungary, without replacing Hungarian as the crownland's administrative language. Or make it bilingual, which would be a really neat idea in a TL.
Also, I want to point out that a massive Austrian victory in the SYW has just-as-massive butterflies and assuming that the 19th century would be the same/similar as OTL is butterfly genocide. Case in point: The French Revolutionary and Napoleonic Wars could go entirely differently, which would butterfly away the creation of the Austrian Empire, keeping Hungary and Bohemia effectively separate states in personal union. In other words, I believe it's more likely that an Austria that dominates the other German states by the end of the 18th century is more likely to focus on centralising the HRE and keeping the Habsburg crownlands outside of the Empire, well, outside, and maintain the personal unions instead. In that case, the Hungarian Revolution is entirely butterflied away. In that case, the main question becomes: What happens to the Czechs? Bohemia was part of the HRE, so they didn't have the same freedom and independence as the Hungarians and are then more likely to suffer from and fight back Germanisation.