Lakhdar Brahimi has set very low expectations for peace in Syria. He's saying, "Look, I'm not a miracle worker. Don't expect me to solve this mess. But I'll try to get something going." This is a wise move on his part, because he has ended the silly notion promoted by the Western media that the removal of Assad will magically turn things around and put Syria on the path to the creation of a new democratic state.
The current government, despite all its flaws, has way more popular support than the foreign-backed rebels who are massacring minorities, alienating populations in the cities, and looting towns.
It is highly unlikely that the character and strategy of these so-called "rebels" will change. Their mission is to create chaos, uproot the state's institutions, and spread terror. They are not a revolutionary political force, but just a desperate group of gangs and Islamist militants who love to destroy rather than build. They are a negative force. And negative forces cannot win hearts and minds.