This is a purely speculative post, but it strikes me that Guinea is a likely candidate for the introduction of semi-presidentialism.
The death of President Lansana Conté has precipitated a coup led by Captain Moussa Dadis Camara. One of the junta’s first acts was to appoint a new prime minister, Kabiné Komara.
Guinea is one of the few countries that has a prime minister who is not responsible to the legislature – meaning, in case of any confusion, that the legislature cannot vote him and the government collectively out of office. There is no provision for a prime minister in the 1990 constitution.
President Conté appointed a PM in 1996, abolished the post in April 2006 and recreated it in January 2007. The office of prime minister was seen as a way of allowing for some sort of power-sharing within the system in the context of social unrest.
Now, assuming that there is any return to democracy and that there is either a new constitution or an amended constitution, then it would be highly likely for Guinea to adopt a French-style model (though, admittedly, it has avoided doing so from the time it was the first French colony to declare independence in 1958), or for the post of PM to be made responsible to the legislature if only as a democratic sop to NGOs and foreign governments. The fact that the junta have appointed a PM so swiftly provides some sort of indication that they are committed to keeping the post in the future.
Unlike the situation in Mauritania, where there is considerable pressure for the junta to return to democracy, similar pressures have not yet been put on the new junta in Guinea. However, when the time comes, it is at least possible that Guinea might be added to the list of countries with semi-presidential constitutions.