It's something I've never understood how did old nubian which became the court language of the nubian kingdoms in the 700s and was the court lanaguge for 700+ years somehow decline and become replaced by arabic . In the span of less than 200 years. That's almost a thosuand years of literature and administrative tradtion wiped out. In such a short span of time.
If Adal had expanded beyond Suakin and the Nubian regions on Ethiopia’s border (and the Portuguese Empire hadn’t intervened during the Futuh), it would instead of just raiding it, have fully conquered the Funj Sultanate and the linguistic make-up of Sudan would be very different today. Muslim Horn African expansion into medieval Sudan would have still Islamized them but they would have retained their ancient languages like the modern Cushites and Semites of the Horn without any pressure to adopt Arabic beyond religious purposes.