Wow I had no idea they were so close to bringing Revan in before. Thanks for a new hope!All the hints are Old Republic era in some shape or form. Whether its pulled from KOTOR RPG's, Old Republic MMORPG, other legends material, or something brand new has yet to be determined.
Darth Revan is all but Canon at this point with his deleted scene cut from the Clone Wars TV show and the inclusion of the planet Malachor V in the Rebels TV show. Darth Treya (KOTOR II) is also nearly canon too since the same voice actress was used for the Sith Holocron in Rebels. I hope their stories are covered in some fashion.