Well, I think Gandalf was underlining just how important it was to destroy the Ring. Especially at the Council of Elrond, every option is examined and pulled to pieces until the only one left is that someone destroys the Ring at Mount Doom.
Sauron would be impossible to get close to physically, certainly for a Man (though I wonder if Frodo and Sam might have managed it?) and he would have been canny enough not to emerge onto the battlefield after his experience at the end of the Second Age. He had minions to do his dirty work, like all good Dark Lords.
The only option apart from destroying the Ring would have been to struggle mentally with him, and that would have been incredibly risky; as shown he managed to destroy the minds of both Saruman and Denethor.