https://www.reddit.com/r/fireemblem/comments/79n5od/fe16_leak_information/

This is all info coming from Serenes Forest, which gets it's info from a supposed middlewoman, who posts her info on 4chan. This information is compiled by Lord_Grima on SF. Take this all with a grain of salt.

Story

A Gothic Horror theme. Darker and more mature, but not "M" rated. More like the Jugdral games.
Two sides - Humans and Kibaire.
Avatar plays a more Villainous role. Camus-like anti-hero.
the Fire Emblem - a sundial. Gathers energy from the sun and the moon. Can either empower or destroy the Kibaire. Both Sides are seeking it.