I think Poland will regain Silesia if the Habsburgs gain Poland..they plan to give it back but on their own terms like what they planned on Galicia.
Jesus Christ, what?! First and foremost- which Habsburg ruler actually considered incorporating Poland (not mentioning whole PLC) into Austrian empire? Only one I can actually think of, was Maximilian, but PLC was supposed to be only loosely affiliated with rest of the empire (decentralized Poland, ruled from abroad). In such case there is
no chance for Silesia switching ownership. Even during Vasas reign, when some Silesian duchies were ruled by Polish monarchs, it was only lifetime, not changing owner.
Now- back to topic. Getting Prussia is pretty simple. During Deluge, elector of Brandenburg was vassal of PLC (but only in Prussia!

), he participated in Battle for Warsaw in 1656, where Polish forces were pushed back, but not defeated. Sweden and Brandenburg positioned their forces to gain strategical advantage, but in case of defeat they were literally screwed- they hadn't had enough supplies to last (they "won" one day before these run out) and had swamps behind their backs. Both Swedish king and elector participated in this battle and it really was touch and go (lack of discipline among Polish cavalryman prevented Hussary charge from completely breaking Swedish lines... And it was really close anyway. Swedish king was supposedly hurt during charge!). If Sweden- Brandenburg lose this battle, it's pretty straight-forward now. Prussia is annexed, parts of Brandenburg too (parts of Western Pomerania, nothing more- we don't want to annoy whole HRE, right?). War was about ownership of Livonia... Which might go either way- in 1656 PLC was financially broken. But- most importantly- no decade lasting war will happen! In result PLC got severely depopulated (quarter of population died, was resettled, or somehow displaced) and reduced in size (Livonia mostly lost, huge areas in the east on behalf of Russia- much worse enemy actually).
Let's go forward and take worst scenario- Livonia is mostly lost (lack of funds), but less so, than IOTL (split between Sweden and Poland). Eastern territories are also lost- but still much less than IOTL (most of eastern Ukraine goes to Russia- but Smolens and Kiev stay in PLC borders- which is much more important than empty steppes, settled by Cossacks). Prussia is annexed, same for bits of Pomerania. Liberum Veto is not instituted (it got stronger because Casimir Vasa used it during Sejm session...) and- most importantly- PLC
isn't depopulated. This is most important point, because huge swaths of unsettled land (eastern Ukraine) were prohibiting from switching to intensive farming methods- it was cheaper to buy new land and settle it, than invest in improvements in soil cultivation, Not in the long range, but still... There's an interesting table in "God's Playground" (Norman Davies), indicating that income from land returned to its pre-Deluge levels about 50 years later (or more, I don't remember now), only to drop again, due to Northern War. It's really interesting, because repopulation took rather short time, which means that without (devastating) wars PLC might easily have about 20 millions population by Napoleonic Wars (with more or less same borders).
Early abortion on Prussia is much more important than killing potential partitioner- no one might even think about partitioning Poland (because- You know- it would be as natural as partitioning France).
Silesia is hardest part- Austria is weak, that much is true. But Poland have only two strong neighbors on its borders at this point (if Russian westernization goes as OTL that is. Otherwise they might become dependent on much stronger PLC. Without access to Baltic/Mediterra, their whole trade goes through PLC. Which kills them as much as Prussian tariffs were killing PLC in XVIII century)- Russia and Austria, one obvious ally- France (PLC borders with Austria, not Russia in this scenario) and one wild card- Ottomans. Obviously, if Revolution starts in France, and it goes as otl there (Netherlands annexed, Austria completely screwed), PLC might consider intervening. On behalf of France or Allies? That's not a simple question, because if PLC survives as strong and healthy state, it won't resemble any other European state. Even without depopulation, PLC will be mostly countryside based (cities were always weak in PLC- Danzig and Warsaw being only ones to cross 100k threshold before partitions), at least before industrialization (we might see peasants migrating to towns/cities as it happened in GB though), with power divided between nobles and ruler (but absolutely not like IOTL. Decrease magnates power, take away unlanded nobles laws and middle nobility will gladly delegate more power to central institution- to weaken magnates even further), PLC might do what seems best- screw Austria by allying with France and grabbing Silesia (nothing can save Habsburgs in this case from breaking their empire- Napoleon won't need them). All this carefully watching Russia...