The official answer is that Harriet doesn't want to look into this in details before she's finished all her work with AMOL, but both Harriet and Sanderson have shown rather clear signs already that they're not really in favor of publishing any more WOT book beside the Encyclopedia after AMOL.

One reason why Harriet doesn't want to get into this whole thing now is that there are legal/financial matters involved. RJ was under contracts for those books and was paid advances for them. If Harriet decides not to publish, she has to settle this with Tor. This may have been negotiated already, for all we know as Harriet delivered two unplanned WOT books by turning AMOL into a trilogy.

The one who said publicly he wished Harriet would have the Seanchan trilogy written after AMOL is Tor's president (because he is a huge fan of Mat and has read the synopsis and would like to read and publish the full thing). Harriet seating next to him on that panel was definitely non-commiting and didn't seem very enthusiastic. Doherty specified he'd prefer the trilogy rather than the prequels (the first didn't do well, and RJ wasn't so good with the short format and even RJ had put them on the backburner. In the end, most people seem want to know the plot details as they have some impact on the backstory of the series, not really read these books).

Sanderson has said a few times already that personally he would prefer Harriet doesn't have the outriggers nor the Seanchan trilogy written nor any other WOT novel after AMOL (and implied this was RJ's desires, though he left it all in Harriet's hands beside saying he'd wish that she finished the main series), but whatever he told Harriet privately about the issue, further than that he keeps his reserve in public (it's rather obvious he's respecting the fact Harriet doesn't want to get into this at this point).

Sanderson has actually said if Harriet decided to have these books written after all, he'd want to be the one doing it - probably years after AMOL (and I wouldn't by suprised at all that at this point Harriet would move forward only with Sanderson writing them and would drop the idea if he refused. The books would demand a too massive amount of work with someone new, especially since what RJ left for them is fairly succint compared to AMOL).

The fanbase is totally divided on the issue. A lot don't want the books written at all, much for Sanderson's own reasons to advise against it, and many want any WOT Harriet is willing to give (and many stand in between)

IMHO, what Harriet should do is find ways to incorporate RJ's notes on the outriggers and Seanchan trilogy (there's not much for the second, he barely had begun writing down ideas... his notes of the Seanchan culture for the main series would be the main source for these books) in her Encyclopedia and that's it.

The Encyclopedia is a whole separate thing. It was always Harriet's book, even before RJ's disease and she was the one who had a contract with Tor for it. She's supposed to deliver it within a year after the publication of the last book of the main series. That hasn't changed, the Encyclopedia is a sure thing (as sure as we can be about such things, anyway).