Taken from the game’s North American official site:
Fire Emblem Fates: Revelation
A third complete story path will be available for just US$19.99/CA$24.99 for owners of Fire Emblem Fates: Birthright or Fire Emblem Fates: Conquest.
Fire Emblem Fates: Map Pack 1
Map Pack 1 features 11 maps and additional content. These maps shine new light on the cast of characters from Fire Emblem Fates, as well as old favorites from the Fire Emblem Awakening game. Discover new background stories about these beloved warriors, while earning more experience points and exclusive weaponry. Every map offers specific challenges and unique rewards.
What’s most interesting is that Map Pack 1 seems to include all 11 maps from Series 1 and Series 2 of the Japanese DLC, which is consequently all the maps released so far.
At the time of writing, there hasn’t been any new DLC maps since the 11th map, Witch’s Trial, came out in Japan during October of last year, 3 months ago.
Yet the “1” at the end of “Map Pack 1” suggests there will be at least one more map pack, so the chances of additional Japanese (and Western) DLC are very high.
Of course, the signs were already there. Unlike Awakening, we still don’t have a 5-star difficulty map and there are a lot of skill scrolls (Paragon to Resistance Drain) that cannot currently be obtained.