Will You Pay for Hulu on the iPad? It May Be Your Only Choice.

Will Hulu come to the iPad? Probably. One day. But you had better get ready to pay for it.

Hulu and its owners, three of the big broadcast TV networks, want to bring some version of the Web video service to Apple’s device.

But the most likely scenario is one in which access to Hulu on the iPad comes as part of a subscription package, multiple people familiar with the company tell me.

Hulu has been free for Web users since it launched in 2008. But its broadcast owners–GE’s (GE) NBC Universal, News Corp.’s (NWS) Fox and Disney’s (DIS) ABC–have repeatedly said they want to introduce some sort of premium version.

Depending on who you talk to, the pay service is either supposed to help the money-losing Web site turn a profit or compensate the networks for the eyeballs and dollars Hulu is supposedly siphoning away. Or both.

The problem is figuring out a way to keep the existing site free while adding new bells and whistles that consumers pay for. One idea the company and its backers like: Turning Hulu from a “one screen” service–one you’re only supposed to watch on your computer–to a “three screen” offering by adding support for TVs and mobile devices.

“Just three screens alone is pretty enticing,” for consumers, says an executive at one of Hulu’s parent companies.

If you want, you can hook up your computer to your big-screen TV with a cable and watch Hulu that way. But Hulu hasn’t aligned itself with devices and software that make the process easier, as Netflix (NFLX) has. Meanwhile, there’s no Hulu for devices like Apple’s iPhone, even though rival YouTube, owned by Google’s (GOOG), loves smartphones.

And while you could argue that the iPad isn’t necessarily a mobile device, since 3G Internet access is an optional feature, Hulu and the broadcasters that own it are likely to classify it as one. Like many other content owners, the video service sees the device as an opportunity to charge for something it has been giving away on the Web.

All the sources I talked to cautioned that Hulu and its owners had yet to agree on a definitive plan for a premium service. And this needs to be resolved before they can tackle device-specific issues.

“It’s a tricky balancing act that we’re trying to fine-tune before we go out,” one source tells me. “Everyone’s concerned about making a strong offering at a good price, and not undercutting the existing business.”

And if Hulu does decide to head to the iPad, it will involve some work for both engineers and lawyers.

Hulu, like almost all Web video, uses Adobe’s (ADBE) Flash, which is a no-go for the iPad, so that would require a workaround of some sort. It’s doable, but not a snap.

And if Hulu decides to define the iPad as a mobile device, it would also need its content owners to grant it mobile rights, which it doesn’t actually have. Again, doable. But the broadcasters are already making money from other mobile services, like Verizon’s (VZ) V Cast. So they have to tread carefully.

All of which makes it very unlikely that you’re going to see Hulu on the iPad when it begins shipping at the end of March, no matter how badly Apple (AAPL) would love it.

A rumor that the service would launch alongside the iPad surfaced in the wake of Steve Jobs’s New York media tour earlier this month. And I don’t think that’s a coincidence. But I don’t think that makes it so, either.