@blenkinsopthebrave-
I certainly hope Bill doesn’t get de-cybermanized, not because I think it’s a fitting end for the character, but because it would gut the emotional aspect of the whole episode. Yes, there’s the possibility this might be her voice in a flashback, but there’s the other possibility this is the Doctor speaking with her in his “mind construct” a la Clara in Heaven Sent.
I do think they’ll find a way to give Pearl the opportunity to travel with the entity from The Pilot, a creature who may have the powers to cure her in a sense – but scrape away the veneer and it would almost be a carbon copy of Clara’s end.
We’ll see…