How large can the Austro-Hungarian Empire get?

[BrotherToAll]

I had an idea in which a much stronger Austria is able to fully get its hands on the whole congress of Poland after third partition, I don't know how realistic that is though, as well as later taking and holding most of the Balkans except Greece, Albania, and southern Bulgaria and Macedonia from the Ottomans.

What would need to happen for the Austrians to take and hold so much?