According to an entry on Jordan's own website (linked above), despite the passing of James Oliver Rigney, Jr., aka Robert Jordan, the Wheel of Time series will conclude even though Jordan barely started the final book. Evidently, he knew his remaining time was limited and prepared accordingly by discussing the plot threads. Those discussions were recorded and will form the basis for book 12.
The Monk's suggestion: see if Guy Gavriel Kay is willing and able to help. Kay worked extensively with Christopher Tolkien (J.R.R.'s grandson and literary executor) to produce The Silmarillion and later became a best-selling fantasy author on his own (Fionavar Tapestry, Tigana, etc.).
Contributions to the Mayo Clinic for Amyloidosis Research to honor Jordan's passing should be made in the name of James Rigney.