They're bringing back Hugh from "Descent". It would be *really* weird if Lore wasn't brought up at that point. Plus, they've already made a big deal out of requiring a "pair" of minds to work whatever positronic magic required for artificial intelligence. Maybe that's the secret: Lore and Data were constructed simultaneous using twin-tech. Not sure what relevance that would have on the story though.
I'm also not sure if scenery-chewing Spiner-as-Lore gels with the grounded tone they've set. That's the one strike against that idea.
Considering Lore ended up being the bizarro version of Data, maybe Soji is the bizarro version of Dahj? Although based on her short intro at the end of the episode, it doesn't seem that way. If anything she seems even nicer than Dahj.