Chuck is produced by Warner Brothers. NBC then pays the WB to air it. So we're looking at two different factions that need to make money in order for Chuck to stay on the air.
(Keep in mind that I am, by no means, an expert on these things, but perhaps living in Hollywood has given me some kind of knowledge through osmosis.)
The WB's formula for making money on Chuck is pretty simple: amount NBC pays them minus the cost of producing the show plus licensing income. I'm not sure if the WB gets all the profits from DVDs, but I'm sure those things probably pull in half a million dollars per season, if not more.
The show is not, however, as profitable for NBC. Their formula for making money on Chuck is pretty simple as well: advertising revenue minus amount paid to the WB plus any licensing fees they might get. Again, I don't know how the licensing is divided up, but I do know that NBC sells a lot of Chuck merchandise in their online store.
The problem, of course, is that as Chuck's ratings have plummeted, the value of commercial air time during the show has dropped. While it has probably not affected the show this year (as such advertising is most likely determined well in advance), it's going to be a hard sell for NBC for next year. After all, advertisers want to reach viewers, so why would they spend their ad dollars on a show that has a small audience?
The recent Twitter campaign to tell advertisers that fans watch the commercials and will buy their products if they support the show has been a good one, but it's hard to judge how effective it will be. Advertisers have responded to it on Twitter, but will that translate to them saying to NBC, "hey, we really want to advertise on Chuck again next year, and we'll keep paying what we paid this year?" I kind of doubt it.
So if NBC's advertising revenue decreases, the only way to keep Chuck profitable is for the amount it pays to the WB to decrease as well.
Ultimately, this means there is only one thing that can save Chuck (aside from executive decision from someone in NBC who is just really nerdy like the rest of us): the WB has to lower its asking price to the point where NBC can make money on the show.
Why would the WB do that? Syndication.
Basically, the WB number crunchers have to figure out how much money they can make by selling the syndication rights to Chuck. Then they need to figure out how much they're willing to lose when they sell the show to NBC in order to make it back (and then some) when they sell the syndication rights.
The problems here are twofold: 1) There's no way of knowing for certain how much the syndication rights for Chuck will sell for, although they could probably come up with a reasonable estimate and 2) Would the discounted price to NBC be low enough for the network to pick it up?
The syndication point for a television is how is generally considered to be 88 episodes, although most networks prefer 100. But if 88 is the minimum, then Chuck would only be 10 episodes away after the end of season 4, and it would hit 100 with a final, full season.
But, again, it all boils down to this: Is it worth it to the WB to make a lower offer? And would it be worth it to NBC to take it?
There's really only one negative that matters when it comes to the fate of Chuck: no one watches it. It has been bleeding viewers all season long. No other network (well, not entirely true, but I'll get to that in a moment) would even consider renewing it, the ratings are that bad.
I could go on and on about the idea that an official, final season of Chuck would bring back a decent number of former viewers and thus increase the ratings to at least an low average level, but that's all speculation and more of a sales pitch than anything else. No, if there's one, glimmer of hope to look towards for Chuck's renewal it's this: Fringe.
But here's the kicker: Fringe is produced by the WB. It has aired 65 episodes, just 23 shy of syndication. That's one full season plus one episode.
Did the WB make a deal with Fox this far out? Fringe has a pretty heavy cult following and would probably do well in syndication. So did the WB
Less helpful but still encouraging is the fact that NBC doesn't have a whole lot of new shows being prepped for next season, so there could very well be an opening for Chuck.
So there you have it: six days left to worry. Let's hope the Fringe effect wins out.