I've been doing some research for a TL for a while, but I'm curious as to what would happen if in the early days of the Janissaries (i.e. before 1500) if suddenly there were no (free to claim the throne) Sultans all of a sudden.
No heir, etc.
A perfect example would be Orhan Celebi, if for some reason he was captive and Mehmed and his only child Bayezid were dead/imprisoned, who would the Janissaries serve?