I am loving this thread, watched.
Just an Amateur's inferences.
Basically, the Adal would leave a lasting stamp of Islam on Ethiopia even if their regime was overthrown.
Also, future Ethiopian rulers would now have a legitimate claim on Somaliland .
The Ottoman influence down south would grow.
Trade between Ottoman Egypt and Ethiopia would increase substantially. Ottoman control over Red Sea increases.
This would maybe lead to earlier reconquest of East Africa from the Portuguese by Oman, financed by the Ottomans. This would also maybe become a challenge to the British ambitions in India later.
The Oromo would either convert to Islam or fight desperately against it.
Egypt would once again become the center of the Coptic world.