Also interesting to note that, based on the description of the map, the Sword Coast goes from Amn to Icewind Dale, and from the Moonshaes to the Dalelands: that's a pretty fat chunk of territory, and would explain the Purple Dragon Knights.
The interview about the book that was included in Dragon+ revealed that it will be closer to a 5e FRCS than just a SC guide, complete with an update of the changes that the Sundering brought to the lands and pantheons of Faerun. The focus in the description of the regions will be mainly on the SC and North, but, according to what was said, there will also be info regarding stuff outside of it.