There's a new Bravely Default game on the horizon! This morning Square Enix and Silicon Studio announced Bravely Default: Fairy's Effect, according to Gematsu. Alas, Fairy's Effect is being planned for a release iOS and Android.
Square Enix lists the title as a "fantasy RPG", which is unsurprising because it's a Bravely Default game. There's a closed beta test for Bravely Default: Fairy's Effect scheduled to begin soon in Japan. The game is due for release in 2017.
On the bright side, Square Enix' latest mobile RPGs have been well-done in the past year or so. The Final Fantasy games - Record Keeper, Brave Exvius, and Mobius - have all carved their own niche on mobile, while holding onto a certain degree of quality.
A mobile release for Bravely Default: Fairy's Effect does not preclude either a 3DS or Switch release of the title. It also doesn't mean that Square Enix and Silicon Studio aren't working on a full sequel of Bravely Default for either platform. There is likely a Bravely Third in development, even if it won't be called Bravely Third when it releases.