This may just be me getting hopeful, but after reading this at the LA Times blog, and catching the following quote, I think I have reason:
“We’re too busy talking about the giant Broadway adaptation, the much longer film version and the musical commentary that we’re writing now.” (As in, a sung DVD commentary.)
“But have I thought up the sequel?” he answers. “Yeah, sort of.”
This is from Joss Whedon himself. So it looks like we can expect more out of Dr. Horrible in the near future. Good thing I’m close enough to New York to get in to see this when it appears, if I can get tickets…