Gollum

If the Ring has been destroyed, & Gollum didn't have the chance to jump into the fire to try & save it, he would most probably have lost consciousness & never regained it lol. The Ring made him merely continue, but once it is no more, he cannot continue as all the motivation & treacherous power of the Ring is taken away. He even said himself that once Ring died, he would die with it. Bilbo had not yet got to this stage of destruction, but if he was present to see it destroyed, he would see it as the end of a nightmare like Frodo.