Joss Wheodn's sequel to Dr. Horrible's Sing-Along Blog has been a long time in the making, and slowly but surely it's making its way into production. Co-writter Jed Whedon recently offered an update to EW ,saying that the songs have been written and the plot has been outlined. This is what he had to say:
“We know we have spoken publicly about a sequel in the near distance and our passion to create it, and I promise we have not been insincere. Horrible is still one of our favorite creations by humans who were also us. We have many songs written and the plot outlined, but needless to say, we’ve been busy. Joss has had a hectic couple of years and is in the middle of the busiest year of his life, as is Zack and as are we. Also the actors have other things they’re acting in, I think. So the future is uncertain, our passion remains. DH2 will exist, in some format or another, at some point in the future. Unfortunately, the when is still unclear.”
Wouldn't it be awesome if Whedon took a two week break in the middle of shooting Avengers: Age of Ultron to make the the Dr. Horrible sequel just like he did for his adaptation of Much Ado About Nothing? I doubt it will happen, but we can always hope. In the meantime, it looks like fans are just going to have to be patient.