I could see Menelikian Ethiopia expanding south into what is OTL Kenya, Uganda, Rwanda and Burundi --the Lakes Region. And the Blue and White Nile region if Egypt did not come back. Possibly all the way to Katanga and Lake Malawi and down the Congo by default, Tsarist Russia fashion.
If the Germans helped the Ottomans with a railroad across the Sahara, I could see the Ottomans doing the same thing in Central Africa, conquering Darfur and Baguirmi, all the way to the Ubangi and Kano and Zinder. And Morocco expanding to it's maximum sphere of influence across the Sahara to the Niger with railroads with the French passively sitting on Algeria. Perhaps a Greater Liberia in West Africa encompassing the Ivory Coast and Guinea up to French St. Louis and Moroccan territory and east to the Gold Coast.