I think the blacked out part is talking about the summons/Eikons themselves. I'm sure most of the Dominants that are not Joshua haven't been shown yet. Though judging by the banners, I'd say Waloed's Eikon is Odin, while Sanbreque's is Leviathan. Not sure if the Iron Kingdom has one though, but it could be Ifrit. I also imagine Bahamut or Shinryu is attached to the Mothercrystals considering the dragon name scheme for them.

What did strike me as interesting is that watching the trailer again with subtitles to get around the thick accents, the existence of Ifrit is apparently an anomaly. Clive is surprised to see another fire based Eikon which makes me wonder if the world has some kind of rule about this. Likewise, some of the background details give the impression that while some nations acknowledge the Eikons, there may exist more than they are aware of.