....now that I think about it, even if the Turkiye's capital fall and all its sultans and nobles fall, there's no guarantee that Balt-rhein gonna win. There might be some problem with supplies (which I'm not really sure how much of it still rely on them), but the other countries could help with that and all he really needs to do is to have the messenger (who will come like days or maybe even months late since the news) silence.
Even if the duchess conquer Turkiye's capital and slaughter everyone completely, the rest of the cities around there would probably hate them quite a lot (even if it's not united, people will rebel against them), and they will be left only with a city of rubble. Plus, the duchess is loyal to herself first empire second. If a truce can be made, then the empire is screwed.