I'm wagering that LSH makes her debut as the season finale. Any takers?Here is my show theory:
There will be no real LSH. Instead, it will be revealed to be Littlefinger controlling the BWOB. He can then leverage Brienne to get Jaime to fall into a trap. It works in his interest to get both out of the way (Brienne because she is something between himself and Sansa, and Jamie because dead Lannisters creates chaos).