In addition to Druig and Deviant, there are other classic Marvel characters that could appear as villains in Eternal. The Celestials haven’t done much in the MCU so far, and most of what we’ve seen is the villain side. Therefore, if Marvel is hatching the intention of this group of cosmic creatures to play a larger role in the future, the Celestials may be shown as direct villains in ‘Eternals’ as the villains. pulling the strings behind everything.
Another possibility is that ‘Eternals’ will bring in the appearance of groups of Titans or Uranus – exiled Eternal groups that split from the Earth race thousands of years ago. In the comics, they also have their own backstory filled with civil wars and betrayals, and with a few changes those stories could appear in ‘Eternals’. Bringing in so many new characters might be too much of a task for a movie to handle, but it’s also a high possibility.