This is not my interpretation, but I found this one interesting.
Ithlinne's Prophecy
Verily I say unto you, the era of the sword and axe is nigh, the era of the wolf's blizzard. The Time of the White Chill and the White Light is nigh, the Time of Madness and the Time of Contempt: Tedd Deireádh, the Time of End. The world will die amidst frost and be reborn with the new sun. It will be reborn of Elder Blood, of Hen Ichaer, of the seed that has been sown. A seed which will not sprout but burst into flame.
Interpretation:
The new sun = The Nilfgaardian Empire.
A seed which will not sprout but burst into flame = Cirilla Fiona Elen Riannon - The White Flame Dancing On The Graves Of Her Foes.
---------- Updated at 07:01 PM ----------
I think that means that Ciri becoming the Empress is the best possible ending to the game, hence why our friends are there along with our romance option.