Şehzade Mehmed, widely considered favored son of Suleiman the Magnificent, died in 1543. While it's not clear how he died, what is clear is that his father deeply mourned his death, since he built the Şehzade Mosque as a memorial to him and composed an elegy for him. This has led many to believe he was favored by Suleiman, and that he was intended to succeed him as Sultan.
What if he had?