Coups beget coups (see, for example, the case of Ghana. More here). Furthermore, coup risk is typically highest after power turnovers, (like is the case in Sudan).
For these reasons, there is fair amount of clustering within countries when it comes to coup incidence. In Africa, Sudan leads the charts when it comes to coup incidence. According to Jonathan Powell’s data, Sudan (14) is third to Bolivia (23) and Argentina (20) in terms of the total number of both attempted and successful coups between 1950-2014 (note that this figure is different from rumored coups or other coup incidences that do not result in an actual attempt).
Because of its history with coups and military rule, it is going to be very difficult for Sudan to cycle back to civilian rule. The military has become used to governing, and will likely want to protect its turf relative to a civilian government, should one emerge.
This is not to say that establishing civilian rule is completely infeasible in Sudan. The generals in Latin America, the most coup-prone region of the world in the 20th century, have managed to shake off the habit.
It is hard to avoid comparing the events in Sudan with Egypt and Zimbabwe — instances in which mass action toppled autocrats but without the realization of full regime change. The next few weeks and months will test protestors’ patience and the overall organizational capacity of Sudan’s Civil Society.
So far it appears like there is not a high risk of intra-military fragmentation that might lead to armed conflict. I would imagine that, as a corporate entity, the military has a lot to lose should they fragment and/or come under civilian control, especially given Sudan’s emerging arms industry. Sudan has the third largest weapons industry in Africa (after South Africa and Egypt). In the short run, this might be a good thing in that it will create incentives for maintaining order within the security services. Total state collapse would be singularly bad.