The news of Mass Effect 3's demo comes straight from Mass Effect Executive Producer, Casey Hudson through his Twitter account. He shared the following message:
Stay tuned for news on demo plans in a few months.
So as you can see, Casey announced there will be an announcement in a few months regarding Mass Effect 3's demo. Seeing as there are a number of combat improvements, especially when you factor in the new Kinect functionality, I'm sure there will be a minority of gamers who will be interested in checking out the demo before splurging $60+ dollars into Mass Effect 3. The majority of us have probably already blindly pre-ordered the game without even thinking about its demo since anything with the words "Mass Effect" on can be considered gamer gold.
[Source: Playstationlifestyle.net ]