Dr. Horrible’s Sing-Along Blog is a very unique case that’s unlike other the shows in Entertainment Weekly‘s latest issue, which explores the odds of fan-favorite shows returning.

For starters, Dr. Horrible was not a TV show (though its 42-minute length is nearly the same as one episode of broadcast television). For secondsies, Dr. Horrible wasn’t canceled — it was created as a stand-alone story. In fact, the story’s ending is satisfying and fitting, unlike the frustrating conclusions of many axed shows on our list (like Firefly). Thirdsly, there’s no huge impediment to actually doing a sequel — the actors are willing, and nobody has to convince a major media company to bankroll millions into the project.

For the few who are unfamiliar: Dr. Horrible was a 2008 family affair from co-creators Joss, Jed, and Zack Whedon, along with Jed’s wife Maurissa Tancharoen. It was a low-budget three-part tragicomedy web musical that on paper should never have been successful but has clocked more than 50 million views and inspired a rabid fanbase despite breaking rules for online success that at the time hadn’t even been written yet. The charmingly quotable story spoofed superhero worship by championing a wannabe villain (Neil Patrick Harris) fighting to win his true love (Felicia Day) from a jerkwad hero (Nathan Fillion).

So what’s the problem, then?

It would be cool to have an answer that’s really dramatic and fascinating. Instead, it’s simply that Horrible‘s writer-producers are super busy. Jed Whedon and Maurissa Tancharoen are the showrunners of ABC’s Marvel’s Agents of SHIELD. Zack Whedon is working on Sundance’s upcoming drama The Red Road. Joss Whedon, when not directing either little indie films or massive gigantic ones, is under contract helping steer the Marvel entertainment universe.

Still, Jed Whedon, who wrote the songs for the project, was kind enough to send us a statement: “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.”