Dalek timeline

"We foresee a time when they will have destroyed all other lifeforms and become the dominant creature in the universe."

- A Time Lord messenger.

As recorded in the Dalek Combat Training Manual, the Time Lords predicted a timeline in which the Daleks would succeed in destroying all other life and so become the dominant species in the universe. (PROSE: Dalek Combat Training Manual) It was for this reason that the Time Lords sent the Fourth Doctor to Skaro to interfere with the creation of the Daleks by Davros' hand. A Time Lord messenger was present to give the Doctor his mission and told him of the time that the Time Lords had foreseen, to which the Doctor admitted that it was "possible". (TV: Genesis of the Daleks)

Indeed, the first Daleks created by Davros acknowledged that their programming did "not permit to acknowledge that any creature [was] superior to the Daleks" and that "all inferior creatures were to be considered the enemy of the Daleks and destroyed. (TV: Genesis of the Daleks)