Anarchism wouldn't' make any difference. The rich and powerful will still have the men with guns.
And the poor, who are by definition more numerous than even the praetorian class, will also have guns. If it comes to a shooting war... well, there's a reason kings don't have a lot of power anymore. 
Just like there can never be a millionaires party, there can never be a praetorian party. Some poor will support one party/clan/religion. Others another. The poor are not a single group and don't approve on one another. Its always been the way and always will be.