Virtually no details of the attraction, let alone concept art of any sort, were released with the news. I would assume that the cause of the release was more to let everyone know that Maelstrom will close for good on October 5th, 2014 since that is only three-ish weeks away. The story also mentions that a new "royal greeting area" for the Frozen crew will be a part of the project.
Maelstrom is a dark boat ride that tells of Norway's history using various scenes and animatronic figures. It opened in 1988 and is one of only a few rides located within the various country themed Pavilions in World Showcase.
Hopefully as time goes by Disney will release some additional information on exactly what the ride will hold!