The grimoire cards that talk about Dr. Shin , his team, and the journey into the Vex network sounds like a very interesting stage for a raid. Osiris was apparently also lost in there as well, and Skolas paid a short visit too. A year or two ago, I played this amazing indie puzzle game called "Rose In Time". If Bungie used that as inspiration for Raid mechanics, it could be one of the most interesting and unusual experiences I can think of. Inevitably, I am sure we will eventually get to go inside the network.