Nah, Id day it's just solidified into a Maybe. There was always that one line in TC that seemed to Juxtapose the two, making it reasonable (if not my own preferred theory) that she was at some point tapped to be the Warden somewhere,
When I read that line in Ebenezar's journal, I think it can reasonably be read in two ways. That is, Eb could have been expressing one of two thoughts in those words.
Eb, when writing this, has just learned that Harry has gone and made himself THE Warden. This is a freaking Big Deal, Harry himself doesn't yet understand how big, of course, he doesn't even know that's what he's done.
Eb writes that he can't think of anybody he'd trust more to handle that position than Harry...and then adds that he thought the same about Margaret. But what
exactly did he mean? It might mean that Eb (and other high-ups in the Council) had in mind Margaret to become THE Warden eventually, had faith in her for the role, and then Margaret went and turned into Margaret and Did The Stuff She Did.
Or, it could simply mean that Eb has just expressed his great faith in Harry, but muses that he once had great faith in Margaret, too, and she proved him wrong. It could be a general sort of thought, not specific to THE Wardenship.
As I said, either interpretation is reasonable. You can make a circumstantial case for either.
For ex, there was the infamous Dinner Party that Margaret threw with Lord Raith, Aramina, Eb, etc. Eb says she suggested Something there, something that made Eb blow up, not just refuse but tell her she was off the beam for wanting it, and storm out.
Well, it
might be that she suggested letting someone or something out of Demonreach once she eventually became the Warden, and Eb didn't take it well. But it's just as probable that she suggested something totally different, unrelated to Demonreach. We don't even know if she knew anything about Demonreach, back then.
