By Tami Katzoff

2013 was supposed to be the year that a sequel to “Dr. Horrible’s Sing-Along Blog” finally came together. Fans and participants alike were excited about it; Nathan Fillion, who starred in the 2008 internet musical alongside Neil Patrick Harris and Felicia Day, had hinted that a sequel was forthcoming, if not imminent, and Maurissa Tancharoen, who crafted the film with the Brothers Whedon (her husband Jed and in-laws Zack and Joss) confirmed to MTV News in late 2012 that work was indeed being done.

But alas, it is not to be -- not in 2013 and highly unlikely in 2014. And you can put most of the blame squarely on the shoulders of the Avengers and their sequel.

“I think that all of us overestimated our multitasking abilities,” Zack Whedon told us. “It’s not on the front burner, unfortunately.” What is on the front burner is Joss’ second Avengers film and Jed and Maurissa’s work on “Marvel’s Agents of S.H.I.E.L.D.”

“There was a time maybe about a year ago I guess, where it really felt like, ‘We’re gaining steam, this could happen in the spring, let’s do this,’” said Zack, whose own schedule is full with scripting the upcoming AMC drama “Halt & Catch Fire” and six-issue “Firefly” comic book series “Serenity: Leaves on the Wind.” Songs for a sequel have been written by Maurissa and Jed -- “great songs,” according to Zack. “But there just was not enough time for each of the people involved to focus on it, and for all of us to get into a room together. So the second Avengers movie is going to swallow up any Dr. Horrible hopes for at least another year and a half.”

Yes, the chances of a sequel appearing in the foreseeable future are slim, but Zack Whedon hasn’t yet given up, and neither should we. “I really hope that we get to do it,” he said. “But it might be Dr. Horrible in a retirement home at that point.”

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