@Brit I wouldn't even say you were "not completely off," I would say your theory was a good 50% of the total picture, which ain't something to sneeze at! If Deidre turns out to be a well... that would be fascinating.
I think that whatever was at the end of the roads, the thing that disappeared.... it's not... that important. I don't know that it would have held all the answers we're looking for - that Sullivan was looking for - anyway. We're finding Magiq in places I'm not sure they were "left" for us to find, and in a way, we're making our own. With every key fragment we find, we're getting closer to the answers.
Also nothing to sneeze at.