What if Smaug the dragon lived?

[Morgoth the Great]

perhaps we are all missing a rather obvious question: how did he survive? perhaps he might of killed Bilbo immediatly, thus Bard would not know of his one week spot, and Smaug would of survived, along with now owning the Ring. but what would he do when he had the Ring? it wouldnt take long to corrput his mind, and he would therefore be a lot harder to persuade by Sauron. another scenario is that Bard missed, and was slain. his town is then burned to ashes, and Smaug returns to his treasure, without anyone causing a threat to him. What would happen to Bilbo and Company then? Perhaps it would not be so different, and Bilbo would perish none the less. Smaug would easily be tempted by Sauron, but Smaug couldnt be the last dragon left in Middle Earth(please correct me if i am wrong there) and therefore if Sauron felt he needed the Dragons, surely Smaug would not of proved such a big difference, as he would be easy to take down with the keen eyes of an elf, and maybe the other dragons were more of a threat