Then the only ray of hope and this is a very dim light beam is that the secular-oriented Baathists have formed an alliance of convenience with the staunch religious fundamentalism of al Qaeda in order to bring down their greater enemy, the United States. The Baathists have a disdain for the al Qaeda philosophy just as Saddam held bin Laden in contempt.
At least in this al Qaeda alliance the Baathists have made concessions. However, the Baathists probably hold the Shi'ites in greater contempt than they do al Qaeda.
Thus any more encompassing unity seems impossible, you are very probably right.