Tuaregs are linguistically very near to the Berbers in Morocco and Algeria. In West Africa the different groups are very mixed with each other, but is clear that the whole are between Senegal and Northern Nigeria is a complex chunk languages. In contrast the easiest new nations should be achieved in countries like Zimbabwe, Angola and Zambia.
At this point, I think that mass secessions anywhere in Africa would cause far more problems than it solves....though I do think the secession of South Sudan was to the greater good (except possibly for oppressive North Sudanese Islamists and 'Arab' supremacists, whose 'good' I just don't care about).