Mobile data caps might be almost universal, but home broadband data caps are much less so. Some providers have them, but many don’t. At the moment, Time Warner Cable is in that “doesn’t” category — but Comcast keeps trying to expand theirs. If the FCC grants the corporate union of the two its blessing, a whopping 78% of Americans could find themselves living under the new normal of limited home broadband.

The math comes from the crew over at GigaOm, who keep up to date on the state of broadband caps in general. They find that among cable broadband providers, TWC and Cablevision are the only ones who don’t currently impose data caps on consumers. (Fiber and DSL companies are a more mixed bag.) Post-merger, Cablevision could easily be the last one.

Comcast’s current data cap — sorry, “data threshold” — is 300 GB. Consumers who exceed that 300 GB data point automatically see a $10 charge on their bill for each extra 50 GB of data used. The plan is not yet nationwide, but the program has been expanding over the past few years and seems to be one Comcast wants to stick with.

TWC, meanwhile, doesn’t keep their data unlimited because they particularly want to. They tried to implement “metered bandwidth” back in 2009 but had to drop the plan in the face of enormous opposition. They have since created an opt-in plan where customers can choose to accept a very restrictive cap in exchange for a tiny monthly discount on their bills. As even TWC’s CEO has admitted, that has been a total flop.

Of course, we don’t know what terms the FCC and Justice department might impose on Comcast in order to let their purchase of TWC go through. It is theoretically possible that regulators could require Comcast to ditch data caps as a condition of the sale. Possible… but unlikely at best.

The cable industry very much wants to implement usage-based pricing for everyone, everywhere — just like we used to have back in the AOL dial-up days twenty years ago. And while it might sound like their reasoning has to do with apportioning a limited resource, so high-volume users don’t prevent low-volume grandmothers from checking their e-mail once a week, that’s not what it’s about at all.

As ever, it’s really all about the money — and the simple fact that the industry would like to make even more of it. And as the future requires ever more data, data caps could be the next big way the broadband industry can make sure to nickel and dime consumers.

If Comcast gets TWC, three out of four Americans could get a broadband cap [GigaOm]

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