It is as possible as 1804 borders. Hell, with a bit of luck it may even be possible with 1768 with an existing Crimean Khanate. But it would have to change some structures.
The 1914 border is likely but it makes the Empires defense harder in Europe. I guess a vast majority Muslim Ottoman State has more positive effects...
I'd go even further back to the time of Selim I. Have Ismail I of the Safavids die at the battle of Chaldiran, resulting in the Ottomans overrunning most of Ismail's domains. Something like this, with the colored lines denoting theoretical borders depending on how successful the Ottomans are in their conquest. They've got to either reach an accord with or actively fight the Uzbek khans' raid parties. The easy answer is to set up buffer states and leave Afghanistan/Herat to vassals that have to deal with the nomad raiders.
This has a couple of major effects:
* The Ottomans turn most of their attention away from European expansion in the short to medium term as the Middle East is essentially a power vacuum
* The Ottomans become far more invested in Silk Road trade and have access to more ports in the Indian Ocean
* The Persian Gulf becomes an Ottoman lake in the longterm
* Iran never goes majority Shiite
* The Ottomans have no major eastern threats in the form of organized states and can use Eastern Persia as a buffer against nomad empires that are slowly becoming less and less severe threats to settled states
* With no major remaining Muslim state in the Middle East to contest the Ottomans, their status as Caliphs is even more ironclad once they inevitably roll over the Mamlukes
* Battle of Mohacs/Ottoman overextension in the Balkans is butterflied
* Selim I's death to disease is probably butterflied too, Suleiman I's reign is butterflied from it's OTL form
This gives you a huge window to play with to change Ottoman/Middle Eastern history. Without the Ottomans overunning Hungary, Christian-Ottoman dynamics change drastically and also keeps the Empire more centered in the Middle East, what with the conquest of Persia to capitalize on. This results in the Ottomans better developing the Levant and Iraq is built up now that it's no longer a frontier province. This also provides an ample window for the Empire to centralize and lean less heavily on autonomous Pashas to rule more distant provinces that are exposed militarily. IMO this is one of the best and most underused PODs for the Ottoman Empire that will result in a net positive for the fate of the Ottomans and the people under its borders.