Some sort of civil war would definitely happen, somalis where tribalistic back then. The difference would be the severity. The casualties would be smaller. Barre would have been overthrown by large coalition of multiple clans. The aftermath would also be more peaceful, heres why
Barre would still be strong as he was not riddled by the financial problems caused by the war. He would still be tribalistic and some day clans would be opposed to him. No dictator last. The clans would need to work together due to Barres strenght. A lot of problems would be avoided by doing this. They would need to agree to power sharign before overthrowing him. There is no guarantee that the agreement would hold but it would stop a lot of problems from happening.