I dunno if this is going to get me in trouble or not, but I'm going to spoiler tag this as much as I can. So, major story spoilers for the conclusion of Shadowbringers to follow.
So, from the revelation given to us by Hythlodaeus, we are now aware that the Warrior of Light (as well as Ardbert) were fragments of the same Ascian soul, one that existed within Amaurot during the Calamity which was the catalyst for Zodiark's creation. However, we also know that the Lifestream exists, and souls pass through a cycle of life, death and rebirth.
Firstly, this assumes that we take Hythlodaeus' words at face value - which I am inclined to do, given the fact that Emet-Selch saw a brief glimpse of us as an Ascian-like figure, even if hubris has blinded him tot he fact and he put it down to a trick of his senses.
Are the number of souls in the world constant? Are all souls that flow through the Lifestream the Sundered remnants of the population of the First Race? Were all sentient creatures even of the same race, or were there others? Can new soulds be created?
This is important because if the answer is that the number of souls is constant, and they can neither be destroyed nor created then surely everyone is a fragmented Ascian soul? Though if they were not the only people on the Source before the sundering that may not be the case. Is it significant that we were AN Ascian... or that we were an IMPORTANT Ascian? Hythlodaeus certainly knew who we were, and Emet-Selch apparently should have, though I think he chose to interpret what he was seeing as we were merely a 'strong-willed' mortal, possibly able to contain the Light.
IF new souls CAN be created, and we do know they can be destroyed as that's what we do with Ascians like Lahabrea and Emet-Selch when using the Blade of Light and Auracite on them, isn't it? Then not everyone that lives today was born of an Ascian soul fragment. That we specifically, and not all the Scions, are referred to as 'seven times rejoined' makes me inclined to think that is the case.
OF course, what if we don't take Hythlodaeus at face value? His name is drawn from Thomas More's Utopia and the character of Raphael Hythlodaeus, with the name Hythlodaeus meaning 'dispenser of nonsense'. Is it nonsense to us? Or is it that because he is merely the only shade of Amaurot who knows this is an illusion, that his words are nonsense to his peers, who all believe the carefully crafted lie of Emet-Selch's fabrication?
...food for thought. Discuss.