The stability in West Asia and the Middle East cannot be saved by power alone, the preservation of the Ottoman Empire will lie in the hands of skilled diplomats and tacticians.
A power we should not overlook are the indigenous sea-faring peoples of America, mainly living in tribes on the west-coast and in the north. These 11 tribal nations are individually small, but if they manage to unite, they might be capable of capturing back their lost lands and calling a halt to western expansion.
Power in east and southeast Asia will be decided by alliances. The abundance of rival powers in the region makes wars inevitable, but the size of the nations and their ability to organize creates a necessity for carefully crafted strategies.
The way in which southern Asia is divided cannot last. The division of opposing powers is extremely complex and unstable. The region has to resolve many power struggles to gain its potential power. There is some urgency in resolving their struggles too, because the next threat might well come from the east.
If the European Empires collapse, the power balance of Europe will collapse with it and internal wars between nations might create a descent into chaos.
There is no continent that is as culturally diverse as Africa, where tribal Kingdoms, Sultanates and various European and Asian cultures all come together. As long as Africa remains divided it will always be a region of contention and exploitation. But if nations in Africa manage to unite and modernize, they have the potential of being a substantial power. Africa is the doorway to trade between Europe and Asia. Those that dominate the African coasts will have the lock and the key.
The indigenous people of Oceania in 1750 are as yet still mostly left alone. This will change rapidly as developed nations start to expand. The indigenous nations are small and have little technology, but there is little to stop them from changing that. If they manage to get ready for defence and expansion they might become a regional power that is not easy to defeat.