Mats Jansson talked about the ability to really differentiate these three classes as they are targeted toward three individually different customer demands - Economy for leisure and shopping, Extra for travellers demanding flexibility and seamless service, Business for those travellers demanding even more. Drew parallel to Virgin Atlantic with Upper Class, Premium Economy and Economy.
Seems SAS are targeting Economy Extra the most. They see this as the unique service they offer currently, and I guess with the new lower prices they will be more agressive with it...