http://www.imperial-library.info/content/thirty-six-lessons-vivec-sermon-thirty-three
'I would have done so myself if I wanted, silly Hortator. I shall keep it there with its last intention intact, so that if the love of the people of this city for me ever disappear, so shall the power that holds back their destruction.'
Nerevar said, 'Love is under your will only.'
Vivec smiled and told the Hortator that he had become a Minister of Truth.
No one knew when it was going to drop, just that it would. It was people love to Vivec that kept it afloat, and after the Oblivion Crisis, the dunmer's love began to falter. Efforts were made to keep it afloat, but it ultimately failed. And the Prophecy was more about toppling the Tribunal's power, rather than defeating Dagoth Ur. Defeating him was part of it, but it was not the main goal.