I don't see why it would result in more dead people? Wars in ex colonies have a horrific toll - just look at whatever the Congo feels like calling itself today!
Too many people see "no decolonisation" and think it means by definition keeping the native population down with a gun, and hence massacres.
But the AIM of most of the colonies were to develop towards self government. Thus 'no decolonisation' per se is not going to prevent eventual self government within the colonial structure, and a gradual loosening of the imperial strings, as what happened with Australia and Canada for instance.
Quite a few post-colonial states are federations - Uganda, Malaysia etc. Local rule is already built into the structure.
Patterns of settlement might be more worth asking about as the first part of this question - obviously if East Africa remains British, more Britons are going to migrate there. There also won't be any kicking out of the Asians.
Best Regards
Grey Wolf