Thornir Alekeg said:
For everyone hoping to see the Firefly films be a success and see Firefly return to TV, don't hold your breath on the TV part. FOX holds the rights to any TV broadcast of Firefly for ten years. If the movie is a success (and I really hope it will be) I don't see FOX just saying OK, you can have the rights to it. They might sell it, which would drive up the costs for any other network, or they might try and bring it back to FOX, but my understanding is that Whedon has very little interest in working with FOX again.
The following post is wholly dependant on FOX being both competent and a corporation... that is, they know how to make money. Of course, Pielorinho's story chills me to the bone, and pretty much speaks to everything that is wrong with our economy and even culture (at least in the US) today, so who knows.
It also assumes that there's no internal interference from Fox, negative or positive. That is, no one is gunning for the show, but no one is actively supporting it either.
Finally, it assumes that while it didn't make good enough ratings on Fox, it made good enough ratings for a smaller network, and recouped all costs of production and then some.
Consider the following three scenarios.
First, that
Serenity is a flop. Humor me.

Well, if it's a flop, then the property is worth essentially nothing, and Fox would be stupid not to sell it, for whatever they can get for it. In which case it's certainly possible for the show to be picked up by someone else, though extremely unlikely.
Second,
Serenity is a success, but Fox chooses to dump the property anyway. For instance, if the movie grosses enough to recoup expenses and a little more, but not necessarily a smash hit. In this case, Fox would probably ask a fair amount for the series, and another network might buy it because the show
would turn a profit on a station where the almighty rating isn't as important. In this case, we might see it show up on something like UPN, WB, or SFC. Either way, Fox makes some money on a series that doesn't gross enough on their channel to cover expenses, and thus would just cost Fox money.
Also, an ancilliary remark on this scenario. One might argue that Fox wouldn't want the competition, sort of like what ABC pulled with
Clerks. I'd argue that Fox doesn't give a good gorram. The cable networks, while gaining ground, still hold very little impact on the major networks. If
Firefly was brought back to TV on, say SFC, it's not going to impact Fox ratings at all, really. So there's absolutely no profit in holding on to the property in this case when they know it won't make them money on the air but someone else will buy it. ABC pulled what they did with
Clerks because they didn't want the program going to Fox, who
were competition.
Side note, it still feels really weird to refer to Fox as competition to ABC.
Thirdly,
Serenity is a success, and Fox chooses to keep the property. That is to say,
Serenity is the smashing success we all know it will be. Now, Fox is sitting on a property that
can make money on their network, and again it would be foolish for them to sit on something that would be turning in a profit. Even if it's not up to Fox standards, they could always show it on FX or one of the other cable channels they own, which demand less ratings (and subsequently, IMO, have better programming, but that's another topic). Now, Joss may be reluctant to work with Fox again, but he'd be in a huge position of control with regards to bargaining. In this case, it's really Joss' decision if
Firefly returns to television.
So you see, realistically it's in Fox's best interest to fascilitate the return of the show.