So confirmed now that Thom will be back next season. Interested to see how he'll be reintroduced (will he just randomly show up in Falme?) and which storyline he will be in. While the main characters are all, more or less, following the same path as their book counterparts, the secondary characters are getting shuffled around a bit. Loial basically got Min's role in Falme while Min took Thom's place as Mat's travelling companion. You could feasibly fit Thom into any of the book four storylines, he isn't really all that essential to Elayne and Nynaeve's. To be perfectly blunt, Thom isn't really essential to any storyline, he's pretty much just guy who tags along offering advice.