I just bankrupted an airline at Lagos (LOS) after about three years of service. Some in the forums have covered the problems with providing service in most of Africa. Having operated an airline there, I learned some lessons that might be utilized to enhance Africa in the game:
1. Interlining being introduced will be crucial. On the one hand, it's unprofitable for most major carriers to serve the vast majority of African destinations. On the other hand, feeder traffic would help make African regional airlines profitable.
It's a win-win: the majors fly their intercontinental jets to the African regional's hub, and the regional flies them beyond there.
2. Allow the majors to lease small turboprops to African regionals on sweetheart terms.
The size of an African regional's profit is small, restricting fleet expansion. (In turn, the majors will want reciprocal interlining contracts.)
3. It could also be useful to tweak the rules on small turboprop production, to ensure the same model (for fleet commonality) is available in subsequent years.
With only a handful of airlines flying planes that small, the demand isn't there for PC-12s that there is for 737s.