It also might be a case of artistic license and allegory. As in, the last time we saw the Scions, including Thancred, they had been Called away from their bodies and we did not know if they would ever be back. Seeing Thancred in the trailer confirms that he (and probably the rest of the Scions Called) will be back, probably in their bodies by 5.0 and that in the time they've been gone, the realm has worsened. It's just that saying doesn't sound anywhere near as good (or in character) as what Thancred says.