Three vs. One

[Raynor]

If Sauron had recovered the Ring and taken over Middle- Earth and enslaved the people, and assuming the some of the Elves stayed, instead of just left for the Undying Lands, could the power of the Three Elven rings been used to combat the power of the One?

If Sauron regained his ring, there is little hope that anyone could have stopped him anymore (save perhaps the valar & Co):

Originally Posted by Last debate, RotK

If he regains it, your valour is vain, and his victory will be swift and complete: so complete that none can foresee the end of it while this world lasts.