Sauron Wins...Then What?

[Belegorn]

There is also this statement by Gandalf to Denethor which I think shows that Gandalf would not have thrown in the towel had Sauron got the Ring back.

Originally Posted by Return of the King; Minas Tirith

all worthy things that are in peril as the world now stands, those are my care. And for my part, I shall not wholly fail of my task, though Gondor should perish, if anything passes through this night that can still grow fair or bear fruit and flower again in days to come. For I also am a steward. Did you not know?