While not much is revealed in the announcement post linked below, this could be either a way to test the technology soon to be used in Delves or a way to expand the bot NPC AI first used in the Comp Stomp Brawl.
In either case, many players have been asking for a feature like this for ages, so seeing it finally come to fruition is nice.
FOLLOWER DUNGEONS
Tank, heal, and DPS alongside follower NPC companions that join you on your Dungeon adventures. They will be available in all eight Normal Dragonflight Dungeons and can scale from 1–4 players. These companions will allow players to learn about Dragonflight dungeons at their own pace and provide the freedom to experiment and customize their Party makeup.