When I said adapt the Thrawn trilogy, I don’t mean I think they’ll try to adapt it verbatim. At the very least, I could see Filoni wanting to set up a similar situation where the OT heroes interact with Thrawn in some kind of conflict.
We saw Thrawn and Ezra disappear with the 7th Fleet at the end of Rebels, so maybe they end up returning to the known galaxy and cause some trouble that Luke, Han, Leia and Ben have to deal with. If you think about it, introducing Thrawn in Rebels and then sending him off into the Unknown Regions alive seems to hint that they might want to use his character in the future. The Thrawn trilogy is probably the most important EU story in Star Wars, so I wouldn’t be surprised if Filoni wanted to very very loosely adapt that story in the new canon in some way. And when I say story, I mean having Thrawn be a post-Endor threat to the OT heroes.