Looking through the website, some things have definitely been confirmed.
*There are multiple realms in Valisthea each with a Mothercrystal. Each crystal is named after an aspect of a Drake, suggesting a common origin for the separate Mothercrystals. They were at peace, but whatever the Blight is, it's raising tensions again.
*Dominants aren't exactly Eikons incarnated, but people with the ability to manifest them. All but one nation has its own Eikon. We don't know which Eikon is given to some nations, but I think we can make a guess given what's on each Eikon-using nation's flag. We know Rosaria has Phoenix, and the Dhalamekian Republic has Titan. I'd suggest based on the flags that Sabreque has Shiva, while Waloed uses Odin.
*In some nations, being a Dominant is equivalent to the Crest system in FE; Three Houses, where it trumps line of succession by age. In others, they're pariahs who can end up being executed for their existence. Kinda like the l'Cie from the original XIII.
*The main protagonist Clive Rosfield is basically the reject head of house, while his younger brother Joshua is the current heir after becoming the Dominant of Phoenix. Not sure where Jill Warrick would come into it, but she's clearly important in some way.
Also, check out this new key art!
