The trouble with dictatorships is that considerable force is generally required to get into, stay in, and exercise power. Usually the military and secret police are employed as the shaft that makes people obey. How much shafting is employed usually depends how much resistance is developed, or how paranoid and unstable the ruling cliques are. The results are sometimes tolerable and stable, but all too often (like, usually) the amount of shafting employed generates more resistance, more paranoia, and more violence in a hell-bound spiral.
So, how does one set up a multi-ethnic government in Kenya, Syria, or...?
One solution is to balkanize the country--and maybe regions. Give small territories to the groups that dominate them (the way the Serbs, Croats, Montenegrins, Kosovoites, and Albanians were sorted out). This makes sense, especially if there are strong historical precedents. Lots of countries and regions have histories that preceded the colonial era, and are remembered.
IF, and it is a big IF, the small homogeneous states can get their stuff together and operate successfully, fine. If two adjacent mini-states want to merge, do so and make it work, fine. Otherwise, don't merge.
Shia and Sunni populations may be at each others throats because they were manipulated into this antagonism (recently). Maybe propaganda can manipulate them back into peaceable community. Maybe not. Maybe separate territories need to be allocated -- not for each and every one, but enough separation so that they, as 2 (3, or 4) separate groups feel like they have their own space.
Maybe the dictator (Assad for Syria) needs to be eliminated, by some effective means or another. There are major risks, here, which is one of the reasons it hasn't happened. The Assad family has a ghastly history, but in most years there were hardly any large scale massacres. Just a few. Pull the Assad plug and there might be a period of (worse) bloody reprisals--even worse than Assad. Iraq had problems before the Americans arrived, true enough, but our abrupt plug pulling on Saddam Hussein and the Baathist party cause a massive deterioration in conditions, as bad as, if not worse than the excesses of mr. Hussein.
Draining swamps needs to be done with great finesse. Just pulling the plug can backfire badly.