Nigeria as a single country was not a great idea: there are far too many factions that despise one another and far too much corruption for Nigeria to function well as even a loose federation. The Ibos of Biafra got tired of the Yorubas of Lagos taking their oil and leaving nothing for them, and there was the Biafra Civil War. Now there is a major split between the Muslim North and the Christian South. This error was first made by the Brits. But no one is likely to do anything about it.
This is largely due to development: now that there are passable roads and cellphones have made communication among the backward Muslim tribes of the North, they want to control the nation more for themselves. And moving the capital from Lagos to the interior had a lot to do with this as well. I have heard that Lagos is one of the worst cities on the planet. Ghastly humid and hot, built on swamps, hideous corruption and inadequate highways, water and electricity.