Howard Stern talks for a living. Sirius XM Radio (Nasdaq: SIRI) CEO Mel Karmazin wasn't about to speak for the star in yesterday's quarterly conference call.

"If you want to hear what Howard's plans are, you should just listen to Howard," Karmazin said of Sirius XM's highest-paid talent.

Karmazin made the appropriate response. If -- and when -- there's an announcement to be made, it will happen during the host's program. It won't happen in a call with Wall Street analysts.

Other analysts may have heard differently, but I didn't interpret Karmazin's comments as "indifferent" or hinting at anything problematic.

"As soon as we have something to announce you'll hear about it," he said. Note the "we" in that sentence.

To my ears, this means one of two things. Either Stern will be re-signed after his five-year, $500 million deal runs out in December, or Stern will retire from radio.

The argument against retirement
If you were running a premium radio service with 19 million subscribers (and counting) what would you do if your biggest star was ready to call it a career by year's end?

You might want to milk the final shows with a wave of publicity and adoration, but financial logic may find you holding back. Many subscribers pay $12.95 a month for the service (before any additional fees), and Sirius promotes prepaid terms of one, two, or three years by offering discounted rates.

If a Stern fan is about to renew for a year come September, it would seem to be in the company's best interest to hold off on news that Stern was leaving, in order to lock up that subscriber until September 2011.

But here's where it pays to kick in with a little game theory. Sirius XM fought negative consumer sentiment when it consolidated music channels, introduced or raised fees, and launched its App Store application as a premium service -- even for lifetime subscribers who have streaming included.

Sirius XM rose above all that, but it would be raked across the coals if it held back on Stern's 2011 plans for the sake of tricking subscribers into sticking around.

That just won't happen. Unless Stern is as unsure of his return as Brett Favre, I think Karmazin knows exactly how this will all play out, and he knows the ill will waiting around the bend if he cheats his listeners by delaying bad news.

The argument for Stern on Sirius XM come 2011
Churn is a big part of satellite radio. It's not as sticky a service as even Karmazin would have you believe. He bragged about an impressive 90% customer satisfaction rate during yesterday's call, but reality paints a different picture.

There were more than 6.4 million account cancellations last year -- more than a third of Sirius XM's subscriber base. The company's 2% churn rate may sound impressive, but keep in mind that this is a monthly figure.

This doesn't mean that Karmazin is lying about the 90% satisfaction. There's just a big difference between being happy with a product, and being willing to pay ever-increasing fees for it. Netflix (Nasdaq: NFLX) has a rabid fan base, yet its monthly churn rate clocked in at 3.8% during its latest report. Satellite television leader DirecTV (NYSE: DTV) -- which would seem to staple its couch potatoes in place, given the costly gear and installations involved -- still checks in with a monthly churn rate of roughly 1.5%.

In other words, consumers are fickle, and it's in Sirius XM's best interests to either improve its service, or at the very least provide consistency. The regulator-mandated freeze on basic subscription rates should thaw out by the summer of 2011, and the last thing Sirius XM wants is to push through a rate hike just months after Stern has gone.

In short, Karmazin will probably do everything possible to get Stern to stay on, even if that likely means substantially shorter hours for the shock jock. Just a little Stern can go a long way.

The lack of options
Outside of retirement or re-signing with Sirius, there really aren't a lot of options for Stern.

He can't go back to terrestrial radio. Satellite radio has grown in stature over the past five years, while conventional radio has either been stagnant or regressed. There may be some shining stars in the industry, but they are small players. The giants that would be logical suitors -- companies including Clear Channel and CBS (NYSE: CBS) -- are unlikely to compete financially with Sirius XM. They also wouldn't be able to offer Stern the regulatory freedom he sought in taking a chance with Sirius five years ago.

We live in a wired world, so Stern can always attempt to strike out on his own. If Stern can sway a million listeners to pay $10 a month for a rich, Web-served experience, he will top his current contract.

The problem, of course, is that Stern risks plenty. He gambled on satellite radio in its infancy and won, but Internet radio as a premium service is virgin soil.

He can partner with a Web darling that will give him greater programming flexibility than even Sirius XM.'s (Nasdaq: AMZN) Audible may be an interesting fit, but the only logical outlet would be Apple (Nasdaq: AAPL).

Yes, Apple.

The iEmpire is shutting down the Lala streaming service it acquired just five months ago. Why would Apple buy a company to squash it? The best bet is that Apple will be incorporating Lala's streaming technology into iTunes this summer. This could actually work for a juggernaut like Stern, and between Apple and Zune daddy Microsoft (Nasdaq: MSFT), you have two of the richest companies on the planet.

A bidding war between CBS Radio and Sirius XM may very well be bumped by a bidding war between Apple and Microsoft.

Is this likely? No. Is it possible? Absolutely.

However, my gut feeling is that Stern returns to Sirius XM on a scaled-back basis. Sirius XM doesn't want to spend as much as it used to on Stern, and he's unlikely to want to work as hard as he did when he first arrived.

It's the one logical ending to this saga; even if analysts, shareholders, and Stern fans won't let Karmazin rest until they hear the ultimate answer on Stern's Sirius show.  

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Longtime Fool contributor Rick Munarriz is a subscriber to both Sirius and XM. He does not own shares in any of the stocks in this article, except for Netflix. He is also a member of the Rule Breakers analytical team, seeking out the next great growth stock early in its defiance. The Fool has a disclosure policy.