The Duchy of Carniola has a majority Slovene population (and IIRC the majority of Slovenes) and could be the nucleus for a Slovene national movement. Depending on how much regionalism is allowed, the Duchy of Carniola may one day promote local linguistic rights, and other Slovene lands like Lower Styria and the Küstenland may also do the same. But I think this would be a result of what would happen in Bohemia-Moravia in terms of a movement.
As for Austria, it wouldn't matter much if Austria is an Archduchy and thus outranked by Prussia, the ruling Archduke of Austria is the German Emperor after all, as he was back when it was the Holy Roman Empire.
As for Austria, it wouldn't matter much if Austria is an Archduchy and thus outranked by Prussia, the ruling Archduke of Austria is the German Emperor after all, as he was back when it was the Holy Roman Empire.