Not sure if it's been mentioned, but on Triple M they were saying that the Broncos have been pushing really hard to get Thorn in in at least some kind of role. Union is fighting hard to keep him but there are big question marks on the viability of their entire comp, and a switch back to League would be the best long term thing for him.
Not sure if that would bring instability if he were an assistant to Walters, as Thorn seems like the sort who'd be ready to step up to a head position within 3-4 years. Or maybe it will be a good thing - Walters instills the culture, we get back to being competitive in 2 years, hardened in 3-4, then a genuine premiership team with Thorn in charge.