The Timing of Her Magical Reveal
This reveal should not seem arbitrary. Rather, the fact that we're getting an idea of her magical prowess right now is a good indicator that we'll see her use it on something this season. And that something could be Jon Snow. Otherwise, why would they be highlighting her prowess at a time like this? Ser Davos seems to drive the point home when he cryptically says, "You haven't seen her do what I've seen her do." This new reveal about her age makes one thing certain: we don't know the full scale of her magic.