So we end up with a 3-way split. Ethopia and the Transititional Government control one part, the Islamists control another, and Somaliland is the rest.
If Ethiopia were to get Western support and air strikes on their side they could probably dislodge the Islamists.
At least 3-ways - I'm not sure who controls 4-5 Regions of Somalia - it might be the usual Somalian pastiche of random warlords. And there's Puntland as well. 
So we have 4 big factions and an unknown number of smaller factions.
Of course, anyone aware of Somali and Ethiopian recent history knows that no other news (well, except perhaps a Somali invasion of Ethiopia) could have possibly been worse.
The Islamists taking over the whole country certainly would be. After all, they killed peopel for watching the World Cup and have said they'll execute anyone who misses daily prayers.
Even then its very unlikely. They could push away the opposition from the Southern Warlords but once they try to turn their attack against Puntland or Somaliland they would be in trouble especially since those are more organized governments and groups who are well experienced, Somaliland and Puntland fought a war with each other in the 90's. If the war does turn to the North as well American aid and recognition could begin to flow into Somaliland making that more powerful and stable. I really don't know why we don't recognize Somaliland and recognize them, for now, as the most legitamate authority in Somalia.
