It appears Joss Whedon has given up on Firefly and Serenity after giving it a good run.
This is a sad, but not entirely unexpected event. Firefly and Serenity are awesome stuff - cutting edge, witty ... and way beyond the average TV viewer I fear. Something this cool just takes too much work to watch for most people, because it breaks too many of the formulas viewers count on in their shows. Juxtaposing the old west directly onto a space-faring sci fi setting does push the limits. The fact that Whedon made it work beautifully doesn’t negate the challenge such a setting poses to the typical TV viewer’s psyche.
This is why steampunk is such a niche genre too. Well, actually steampunk is worse, since it combines two niches into one. At least Firefly combined the old west (a really big niche) with sci fi (so big it isn’t really a niche at all anymore).
Ahh well, at least we have the Serenity role playing game. I’m running a campaign for my family: their characters are still trying to scrape together enough cash to buy their own ship, and seem to have found a possible way to get it sooner than later. Of course both my kids are still getting the hang of role playing, but given all our shared love of Firefly the setting makes it easier.