The way they describe it, it will integrate a lot of stuff from the notes, especially about the world building and from the character files.

What remains to be seen is how much unused bits RJ really had. If his Cadsuane bio is a typical example, he seemed to collect in there what he invented as he wrote rather than his file being a pool of unused elements to dig in at need.

But I would expect that there is in that file more details about stuff like Toothie and the paralis net, her escape when the Hall wanted to make her Amyrlin, etc. ie: stuff he's alluded to but has not fully explained, so if he returned to that eventually it stayed consistent.

His Elaida notes had a fairly elaborate explanation of what happened in the background through TGH/TDR/TSR/TFOH (elements he never returned to, he had forgotten those details).

RJ didn't reread himself, so he noted new pertinent details to keep track of in his notes.

OTOH we also know that there are no notes on some stuff he considered irrelevant, for e.g. there's nothing about the circumstances of Asmodean's murder. All they had was a fan's letter that listed all the right clues and culprit on which RJ put a post-it with "that's it" on it.

He was more than pulling our leg with his clues, though. He gave us a clue about time distortion near SG with his "where and how".

I'm not sure how much they'll be willing to include of the background of the series that RJ wanted us to keep wondering about. But RJ wasn't so very secretive about what he knew he didn't intend to use. Hopefully they'll follow more that line of thought, that now the series is over it no longer matter to the regular readers, and the new ones just have to wait to read the encyclopedia. Maria sometimes gives straight answers (a recent one was "it's Fain's WC who attacked Demira" and sometimes she RAFO a lot, but she gave the impression they're keeping some of the really good stuff for the encyclopedia (not much point to tell us she found Verin's file fascinating if she's just teasing about something she knows won't be in the encyclopedia, but if they do it explains why she's gleefully RAFOing 9 out of 10 Verin questions)

RJ enjoyed the theorizing and didn't want to kill that, but I doubt readers 5-10 years from now new readers will find large communities willing to discuss at length who killed Herid Fel and stuff like that. Reading WOT is bound to become a more solo experience from now on.

Some stuff I wouldn't have expected to be included but that said they meant to include (eg: Rand's and Moiraine's questions to the Aelfinn) suggests they're ready to give us a lot of details we "shouldn't know".

I expect a great deal of the "new stuff" will concern the various nations, races, history, WT details and such. The AOL too, probably. About all this stuff I suspect RJ had cumulated a lot of background material over the years. We know much of that is in bullet lists form, though... lists of fauna/flora in each area, complete lists of products/imports/exports and that sort of details. Interest in that sort of things will vary massively from reader to reader.