What would the Byzantine Empire have to do to survive?

[hoplite14gr]

Ottomans were an empire. They had to balance two religions while Romans(Byzantines) one-in theory at least.
After a time the Cristian subjects felt they couldn't get justice. Failing the internal peace as you said.
Suddenly the Char, the Holy Roman Emperor, or the other Wesrten rulers started becoming attractive
to the Cristian subjects who suddenly remembered the had a Muslim ruler.
Only a failure of the European rulers to agree to a partition saved the Ottoman empire.
Same way as Michael Paleologos was saved because the Angevin and the Hochenstauffen or the Hungarians
coulld not agree who takes what.
Even in our "civilized" times "combined states" rarely have friendly divorces.
Chehoslovakia is the exception confirming the rule.

Kind regards