Divide Germany into two parts, going along religious lines. Tell the Bavarians, Badenians and Wurtembergians that Prussian rule has only brought misfortune on them, and war they didn't need or want. Let them even unite with Austria. Afterwards, favoritize Southern Germans over Northern ones when...
Generally, realistic alternatives include little more going to Poland or Soviet Union, eventually also more going to Lithuanian SSR within Soviet Union. Once the Soviets occupy it, I see no chance for any German-populated SSR there though.
If you allow for earlier POD with no fall of France and...
Donetsk. Rather often heard name these days.
BTW the city went through quite a number of names. it was called Yuzovka, after its founder, John Hughes, until 1924, then became Trotsk for a short, before being named Stalino, which didn't prevent it from being captured by axis in world war two...
But still, Silesia separates Saxony from Poland, so for ruler of both it would be an attractive gain. Though August would rather add it to Saxony than Poland.
Poland-Lithuania and Austria were already two large multi-ethnic states. To combine them into one unified entity could prove too much. More probable IMO would be a dynastic union, like between Austria and Spain.
The possibility that you write about happened during 1587, when Maximilian Habsburg...
Gemrnay would fall into civil war, and divide into 16 separate states, while spontaneous revolt in Poland would overthrow communism. Russia would accidentally nuke itself. By 2014 Poland would be richer than Germany, and 3 times world champion. Polish mediation would end Arab-Israeli conflict...