Do you think that the Twelve will eventually become major players in the plot?

[Kuwagami]

You think you are joking, but it could be true.

I was not joking. I'm dead serious on this. Halone appears, war happens, Ascians are sided with the ones seeing Halone ? I just think it's a little too... obvious ("Booooo, bad Ascians!").
Though I believe the mythology to be real, in the sense which everyone of the gods (the Twelves, the primals, Phoenix) and former "people" (in a large meaning : King Moggle Mog XII, Saint Shiva, Bahamut) had a real existence at some point.

So while I believe that the Twelve were some kind of all powerful mortal (Assuming they haven't always been deities) I don't believe that any summoned incarnation of them would actually be The Twelve. Like when the Ascians tried to talk the Ala Mihgans into summoning Rahlger the Destroyer. He might have said he was Rahlger, he might have looked and acted like they though Rahlger was suppose to, heck he might even have a lot more knowledge on the other 11/12 in the Pantheon than his summoners, but I don't believe it would actually be Rahlger himself.

If we are to believe that the primals are a big ass shared consciousness sucking aether dry to maintain a form, it's safe to assume that it takes the form and memories the followers want it to have. In this sense, Rhalgr would have looked, behaved and known everything he is said to have in the mythology of the twelves. Though it wouldn't have made him the real one as all that isn't said in the stories would have likely not been here.