He said this about the Mat-Tuon trilogy. He came up with the idea fairly late, and it was mostly in his head still. There is some sort of synopsis, as Brandon read it. Harriet let slip (somewhat reluctantly, she doesn't appear so positive about gettig those books written) Jordan had a massive amount of notes on Seanchan that could eventually be used to develop the trilogy.

Infinity of Heaven is a a whole other story. Jordan has been developping his ideas for the series for about a decade. He's got copious notes, just the same as he had when developping WOT. Story lines, characters, cultures, magic system etc. Fairly late in the process he had a major change of mind, though. He was supposed to start the series with a shipwreck on the coast of an Empire (à la William Adams, whose story also inspired Clavell's Shogun), but in one of his rare discussions of this series he said he had changed his mind and there he was now developping a trilogy set before the shipwreck event. Based on all this - a story still massively in development - it sounds fairly unlikely it could become more than someone else's series "based on an original idea by Robert Jordan" (sold to a writer or publisher by Harriet). Personally I don't really see what would be the point of that, it would be little more than exploitation of Jordan's name for money. I really doubt Harriet would sell the rights this way, or that it would attract a good writer, especially since a major attraction of Fantasy for writers is in the worldbuilding process (Sanderson for instance would never agree to take IoH over). I think it's a good bet IoH will never see the light of day (though I guess it's likely that at some point some of Jordan's projects etc. will either feature in some way in a collection of his notes published by Harriet (but she is reluctant - Jordan hated to let others read his drafts and notes and it seems to count a lot for Harriet), or perhaps more likely still, be commented on by a scholar/biographer in a book about his writing/his life).

Personally while I'm curious about IoH, I have fairly little interest in this series being written by someone else. There's not 11 books written to guide a writer, it would someone's else's series altogether, not much of Jordan would remain. As for giving this to many writers, it would be the same, only worse.

As for the unwritten WOT material, I would much prefer if Harriet used their content for entries in the encyclopedia. There will be many good backstory nuggets in there - a few of the series's mysteries solved (Tam's backstory, the vileness, the events right before EOTW etc.), and it would also be fun to see a bit how Jordan envisionned the post LB world of WOT... but I don't see why the facts we want could not simply appear as Encyclopedia entries rather than be twisted/augmented/changed by another writer trying to turn barely outlined stuff and notes into a novel). This would not have worked for AMOL - this one had to be developped in full or abandonned, but for the facts to be found in the prequels and the Tuon-Mat stuff, it would be the best way to make them available, IMO.