At this point in time, it is still unknown if "Fire Emblem Fates" will be a single release in the West.  There is a major lack of details on its western release, aside from the fact that it is supposed to be released sometime in 2016.
There will be three versions in Japan: two different retail versions and a DLC version.  Many western gamers are wondering if the western release will only include one of those games or both retail versions combined into a standard version.
There has been much speculation on whether only one version is already planned because of the game's product page on the mobile version of Amazon UK. It currently displays a notice mentioning that the product will be the only one released in the western market segment. Whether or not that information is accurate is unclear, as well as Nintendo's confirmation of it.