Farhad Manjoo has pointed out that for Facebook to maintain its share price, it needs to figure out how to increase its revenue by a factor of ten. Going from $5 per user per year in advertising revenue to $50 per user per year is about as likely as Facebook going from 1 billion users to 10 billion, which I suppose is the other way the company could increase revenue proportionally, even if it requires an alternate Earth’s worth of additional human beings.

So! Either this IPO is, as the Wall Street Journal has suggested, the biggest shell game in the history of stock offerings, pushed along by those who want to cash out their shares in the company at the expense of unsophisticated investors who are piling on, or Facebook has a plan.

I don’t think Facebook actually has a plan. I think it’s the new AOL. But if it did have a plan, this is what it would look like.

Facebook Must Become A Bank

Forget Square, the credit card processing dongle for mobile devices produced by a company headed by Twitter alum Jack Dorsey. What the payments industry needs is a fast follower with serious reach and the desire to vanquish every other player in this space.

Or, as Dan Hon, interactive creative director at Wieden and Kennedy recently told me, “It would be really interesting if Facebook launched a credit card. In fact, it would be terrifying.”

Facebook already has a credits system designed to fuel the compulsive addictions that afflict some of its users (and which are otherwise known as games like FarmVille). Tim Carmody did a good job of explaining the possible scenarios for an expanded credits system, but that’s not what I’m talking about.

The appropriate analogy is Apple and iTunes.

“iTunes has so much credit card information that if they weren’t such a singly focused company you could imagine them taking on the retail banking business, and Apple-ifying it.” says Hon.

An Apple-style stunningly easy and simple to use payments system has the potential to take over, but the result would be something that only worked in one way – as the ghost of Steve Jobs intended it. Facebook’s take on this system would probably be a lot less tightly controlled (and not nearly as inspired). There’s also the small matter that, unlike Apple and Amazon, Facebook doesn’t have your credit card – yet.

Under Zuckerburg’s leadership, Facebook remains a surprisingly nimble company, considering its size. But as Manjoo points out, going public means, inevitably, bowing to the pressures of shareholders, who want their money’s worth. Look for Facebook to acquire Square – or try to kill it. Or, if they’re really savvy, make a lateral shift on a scale of Apple’s entrance into the phone market.