We started getting details about it in the same book where Demandred was introduced. It was obvious that he was being established as a grudge/rival enemy for the end. Likewise, Shara being described by Graendal, as a place of mystery and deception, run by a channeling class, just seemed ripe for a Forsaken takeover, and Sammael's dismissal of the place as a red herring seemed itself to be a red herring. I didn't theorize much about Demandred's actions or power base ahead of time, because I didn't make any connection, and also it seemed like he was going to pull something out of nowhere. In my mind, Shara was too obvious and neat.
There were three things in particular that I never liked about the Shara theory for Demandred: 1) There was no known persona in Shara, and RJ implied that he had one that could be figured out, despite it never having appeared "on screen"; 2) it was too easy, no development required; and 3) we didn't really know enough about the Sharans to care about them if they did show up, which led to a major off-canon infodump on the subject in "River of Souls" (not that AMOL was spared of infodump).
Graendal actually would have been the best person to infiltrate Shara, IMO; she is the one who made it ripe in the first place. Her skills were well-suited for it.
I know, but the whole channeling class of the Sharan continent? It's too much to come out of nowhere. At least, that's how I always felt about it.
There are a few reports, some transcribed, where he talks about his health at that point, and how he was forced (by Harriet, basically) to quit working all day every day. Thereafter he said many times that he was never able to fit as much into a book as he wanted, not in time to make Tor (and fans) happy.
