Harriet's/Maria's encyclopedia is confirmed for release in 2014 or early 2015. By contract she has to deliver the manuscript to TOR one year after the last book of the main series was published.

It won't happen while Harriet is alive. She intends to respect RJ's wish that only AMOL would be finished if he died, and then that there wouldn't be anymore WOT beside possible adaptations. She agreed to River of Souls because it was charity and the "novella" was actually cut scenes from AMOL. If any other WOT project was to happen it would have been this year, before Harriet Tor negotiated to void RJ's publishing contracts for several more books (for which Tor had paid RJ substantial advances, that's why Harriet hesitated for while, but after AMOL came out she announced she would not have the prequels/outriggers written, nor any more WOT after RoS, and she won't sell the IoH project to anyone either. There was also an unfinished early novel in there, but Harriet said it's very unlikely to ever get published).

The Encyclopedia, for which she intends to milk RJ's notes massively (and probably the little he left about the plot of the prequels; for the outriggers it was only a 2 sentence synopsis...), is a separate thing. She's the one who has a publishing contract for that project, predating RJ's disease.