For my money, it would focus eastwards rather than westwards - perhaps there'd be some degree of expansion along the Greek and Wallachian coasts, and maybe even a fully Turkified Greece, but the Balkans are pretty difficult for an invading power to effectively conquer. Look at the examples of Austria-Carnolia in the 1600s, the Crimean Empire in the early 1700s, or even Naples throughout the 19th century - outside powers can get a foothold, but never actually capture the entirety of the Balkans, and I suspect the same would be true of this Ottoman Sultanate. By contrast, the eastern option is full of minor states like Trebizond, Ildegizida, or the Republic of Antioch, which would be a lot easier to steadily swallow up - and doesn't raise the issue of getting drawn into Central European politics, which is a minefield at the best of times.What about the focus of this hypothetical lasting Ottoman Sultanate? Would it have consolidated it's rule over the Balkans or would it have tried to conquer the various petty Turkic realms of Eastern Anatolia?