The elves have troubles of their own to deal with and the magicians of the land have also gone out of control. So there is the chaos of every kind which cannot be curtailed at any cost. Geralt and Yenneder have a bigger mission at their hands so they have stopped thinking about the thing.
They are actually protecting Ciri who is the true heir to the throne. According to prophesy made long ago, it is up to Ciri to save or destroy this ancient land. So whatever service she performs in the future is still not known to anyone. However, as long as she is alive, there is hope for everyone and Geralt wants to keep that hope alive in the hearts of his people.