Only if Damon or Elena died, or if Damon/Elena's character gets ruined.

No,but I will be very sad ^^

my favorite character is kat
and probably she died in the show

but I stop watching the show if matt die, because he is my favorite character on the books, and I really love him

and of course if stefan or damon die I stop to watching the show too

Klaus will die eventually

It's too bad that Caroline, Klaus, KLatherine...all of them could possibly die. But Elena never will :( haha XD
Anyway, I will continue watching! I mean they can always come back. You never know ;)

If Caroline died, I'd be heartbroken but it's my fave show so I couldn't stop watching it.

Maybe. It honestly depends on how it happens and if the story is at a place that interests me without said character. Which it isn't right now. Meh.

as long as Elena, Stefan and Damon are in the show I will always watch. If one of them did die I would watch the next few just to see how it goes, but most likely not. I have watched shows were the actors wants to quit their job of the character they're playing and they are like the main character of the show and it's just not the same.