What are your crazy theories after Endwalker

[Alleluia]

Venat said she shipped Minfilia and one other soul from the First to the Source. So mixing of souls between reflections on their own is unlikely.

But on the other hand, that meant Hydaelyn was able to reach and manipulate all lifestreams from her position. Which means there is a place where all lifestreams are near to each other, if not actually connecting. Hydaelyn was the moderator that kept them stably separate, but the position is vacant now. I wouldn't be at all surprised if the separation between the Shards' lifestreams starts to break down with her gone and the streams of souls/aether just start flowing where they want.

Could possibly even result in a gradual merging of like soul shards, something they seem able to do if G'raha's easy blend with his own soul is any indication. And I am talking a very gradual merge, over many lifetimes, and well outside of the scope of our story beyond a random academic NPC maybe positing it'll happen. Cus two shards of the same soul would have to be near each other, in the same lifestream, at the same time; and the odds of that occurring are low, and get lower the more often it occurs.