The first ever Marvel Studios novel titled Thanos: Titan Consumed written by Barry Lyga may have given fans an important clue that either the Horde or Celestials will be the new villains in next year’s Avengers 4. Although we don’t know much about the film yet, some evidence has suggested that Thanos may not be the only villain in the film. Leaked descriptions on a toy box have teased “an even greater threat” and “new foes”.
The clue that appears in Barry Lyga’s novel Thanos reveals a bit about his history. Lyga has previously worked with Marvel and the plot shows an intimate knowledge of Infinity War’s narrative. It reproduces Gamora’s recruitment and teases a cosmic experience for Thanos after he has snapped his fingers. Given that Lyga knew about Infinity War before its release, its safe to assume that he had some knowledge of Avengers 4 too.
Towards the book’s end, Thanos is seen talking to a being called Lorespeaker who has intimate knowledge of stories and legends of the cosmos. He tells Thanos all about the Stones. Here’s what he says when Thanos asks him why no one uses it:
“They are hidden, Thanos,” the Lorespeaker said, as though badgering a child, “because they are too powerful. And because the Celestials and the others, the ones whom the Celestials fear, keep a close watch on the Stones from afar.”
All we get to hear from Lorespeaker is correct according to the MCU and if he’s right about this too, then powerful forces still exist in the cosmos who keep a watch on the Infinity Stones. So it’s possible that Ego wasn’t the last of their kind and the reference to the “ones whom the Celestials fear” is probably to the Horde, who are the agents of destruction.
So if this theory holds true, Avengers may find themselves going off against either the Horde or Celestials