Just like other countries the case of Biafra will not be different, I can assured that the separation of Biafra from Nigeria is certain and it will not be the only region that will be separated from countries.
Below are some countries that have successfully separated from one country or the other.
Singapore was once part of Malaysia
Pakistan was once part of India
Bangladesh was once part of Pakistan
East Timor was once part of Indonesia
Sudan was once part of Greater Egypt
Eritrea was once part of Sudan
South Sudan was once part of Sudan
Cameroon was once part of Nigeria
Namibia was once part of South Africa
The Gambia was once part of Senegambia
Ukraine was once part of USSR
Bosnia and Herzegovina, Croatia, Kosovo,
Macedonia, Montenegro, Serbia and Slovenia were once together in Yugoslavia
Crimea was once part of Ukraine
Czech and Slovakia were once together as Czechoslovakia
The United States of America was once part of the British Empire
Turkey, Saudi Arabia, Iraq, Iran, Syria, Armenia, Jordan, Israel, Palestine etc., were once part of the Othman Empire.