They are not going to release a demo because of how many people that are speaking on how garbage the games multi player is. Go to EA's forums and the current PC demo is getting ripped apart every day something serious. They will lose more sales by people actually playing a demo.
The single player campaign looks great ( made by EA ) but the multi player ( made by Dice ) looks like shit, Dice is garbage and EA made a mistake by rushing this game out and having them produce the multi player side.