Announced at the end of today's Nintendo Direct Micro, the sequel to Bravely Default will be released in the US and Europe in 2016, as Bravely Second: End Layer.
Bravely Second's story takes place two and a half years after the original. Agnes Oblige, now the Pope of the Crystal Orthodoxy Church, is kidnapped by the mysterious Emperor Oblivion. The task of rescuing her is left to the Church's Stalwart Aurochs (Three Musketeers), the bodyguards of the Pope: Yew Geneolgia, Janne Angard, and Nikolai Nikolanikov. On the journey, Yew runs into Magnolia Arch, a Ba'al Buster from the Moon, and along with some old faces, they seek to save Agnes and stop Emperor Oblivion's plans.
Expect to see some new Jobs, some new locations, and a few new features. In particular is the chain battle system, where if you defeat a random mob in one turn, you have a choice of immediately fighting another mob for a multiplier bonus, with the caveat of your BP carrying over. Oh, and from the import impressions so far, it sounds like this game's mid/endgame doesn't pull the same level of shenanigans as Default's endgame, though it does reuse plenty of assets from the first game.
Obviously, the following information will contain some spoilers for the first game.