The Valar
 

This has probably been brought up many times before but hey I'm bored...

What IF, Sauron had captured the One Ring and used it to crush the forces of good and make Middle-earth his. Would the Valar, like they did in the Silmarillion against Melkor, come to Middle-earth and do battle with Sauron? It caused catastrophic changes in the Middle-earth landscape the first time and I could see it as maybe the last resort. Or are they too removed and/or too uninterested at this point in the history. They sent the Istari to help but left them bound not to use their full powers against Sauron.

That's a very interesting question Grey, if it had come to that, they may have, but Mandos knows all fates within the Great Music, so they may have already knew the outcome. In the Silmarillion, right before Melkor destroyed the Two Trees, all the Valar and some of the Elves were having a festival, Mandos made a statement that to the effect that never had anyone in Valinor had ever been slain until then. He knew that Finwe would be killed and the Trees destroyed before it happened. Only with Manwe's permission could he ever reveal what he knew.

I don't think that Sauron's victory was in any way possible: Eru would have intervened, but in a subtle fashion. Actually, that is exactly what he did - he allowed Bilbo to find the One Ring (at least that's what Gandalf suggests) and he resurrected Gandalf after he had been slain by the Balrog. Neither of these was a massive earth-shaking event, but yet without them the powers of good would have utterly lost.

It is a what IF question, not that it would because it didn't but just if something went really wrong and Sauron did get the ring.