Whatever happens, and no matter how many surprise people get killed off in the meantime, I just can't see Joss ended the series (again) on a bad note. Just doesn't seem like it'd happen. I would love Buffy to continue on in different forms for a very long time, but I also want the quality to stay awesomely high. We all know that there are so many TV shows that just lose their edge and I hate that. On the other hand, when Buffy ends I want it to end for good, I don't want there to be a movie, or another comic book season, or a dodgy spinoff that I watch because once a season there's a cameo from a real Buffy star.
So, at the end of the day, I guess I wouldn't be able to make up my mind even if it was up to me, so probably better to leave it in the hands of a much smarter human being... Joss Whedon.