If there is a new paid expansion planned for next year or later, the collector's edition or special editions could include physical items. I read the article below from Massively.com stating that most players prefer paid content to include media instead of just a digital download. The market research survey was based on a sample of 7,900 gamers.
http://massively.joystiq.com/2014/05...ysical-copies/
Elder Scrolls Online included shipped material with a boxed edition of the game itself. I think an offering like this would be especially suited to DDO as so many pencil and paper D&D players also play this game and they may enjoy having at least a book for a major expansion (e.g., Waterdeep). The highest priced edition of the expansion could include a hardcover book, perhaps a figurine, and other items.
Would anyone pay more for an expansion with physical items? if so, what could be included with the physical version of such an expansion?