The Great Darkness

[luthien-elvenprincess]

I don't think that Melkor or Sauron could ever achieve their entire goal.

...the Valar endeavoured ever, in despite of Melkor, to rule the Earth and to prepare it for the coming of the Firstborn; and they built lands and Melkor destroyed them;valleys they delved and Melkor raised them up; mountains they carved and Melkor threw them down; seas they hollowed and Melkor spilled them; and naught might have peace or come to lasting growth, for as surely as the Valar began a labour so would Melkor undo it or corrupt it. And yet their labour was not all in vain; and though nowhere and in no work was their will and purpose wholly fulfilled, and all things were in hue and shape other than the Valar had at first intended, slowly nonetheless the Earth was fashioned and made firm.

As seen from the above Ainulindale quote, none of the Valar's original and total purposes were ever fully realized, why would the purposes and designs of Melkor or Sauron be any different?