Disneyland is themed to Americana, DCA is themed to a state in the US, a third park must continue the American centered theming. Disney's America is, then, an option but I find it to be rather dull and uninspired as it is already an unused concept. A park themed, however, to both American continents allows for more potential and creativity. It also, if done properly, can mimic Disneyland's lands in the same way DCA and DisneySea attempt to. There can be a 1960's New York land full of Marvel characters (a Tomorrowland equivalent), deep jungles of the Amazon (Adventureland), American west, Canadian frontier, and Mexico (the Frontierlands), etc. Using this concept as a theme also gives way to unused concepts from Westcot and Disney Sea Long Beach.