Here is what he said about the future of the franchise.
"That's what everybody wants to know about. Uh, yeah. My fourth feeling when I read about [the Veronica Mars Kickstarter campaign] was a kind of dread. Because I realized the only thing that would be on everybody's mind right now. I've said repeatedly that I would love to make another movie with these guys, and that remains the case. It also remains the case that I'm booked up by Marvel for the next three years, and that I haven't even been able to get Dr. Horrible 2 off the ground because of that. So I don't even entertain the notion of entertaining the notion of doing this, and won't. Couple years from now, when Nathan Fillion's no longer on Castle and I'm no longer the Tom Hagen of the Marvel Universe and making a giant movie, we might look and see where the market is then. But right now, it's a complete non-Kickstarter for me."
He goes on to talk about the budget it would take to make the film and how he thinks fans would react.
"I think anything we could get off the ground would be appreciated by the fans. But what form it would take is I think under some debate. For me, [Kickstarter] doesn't just open the floodgates. God knows, things are cheaper now than when we made even Serenity. Good effects can be done in a different manner. Nor is that universe all about spectacle either. But it is a tad more expensive - and a little all-consuming! And of course, there's the other fear: What if it's not that good? I can do something that's not that good - that's fine. But if I do that and it's not that good, I'm going to feel really stupid."
Firefly was set five hundred years in the future and followed a renegade space crew that tried to survive their travels through the galaxy and spawned one movie titled Serenity.