I'm using Human as a way to say Hur, Elezen, Mi'quote, Rogadyn, Lalafel, Au Ra and Garlean. Shinryu and the other eikons I've mentioned demonstrate that there's no real need to have "Beast Tribe"-like societies be the only societies to summon eikons. I see "Beast Tribes" as nothing more then the game telling you that they're a group that will have daily quests and a faction system tied to them. For all the Ananta are a "Beast Tribe" their quests are more about the Ala Mhigan Resistance coming into it's own then anything to do with the Ananta (which some people did not like).

That pretty much opens up to door for any group of people with the drive and aether to summon anything. Which I think is good. The "beast tribes are the only ones who summon primals" premise has gotten very stale and predictable (same pattern for three expansions). I'd love to see an expansion where a set of "Beast Tribes" are still there but it's everyone else but them is doing the eikon summoning.