AT&T thinks all tablets will eventually include cellular radios standard

Currently, most iPads and other tablets bought by consumers are Wi-Fi-only. Apple charges a $130 premium for iPad models with cellular connectivity, to offset the cost of 3G and 4G LTE radios, while most other tablet makers charge a $50 premium for cellular-equipped models.

But Glenn Lurie, president of emerging devices at AT&T, told Macworld he believes that as the cost of cellular radios drops, many tablet makers will sell only models with cellular data connectivity built in. That would give users the choice of whether or not to subscribe to a data plan, without needing to pay a greater up-front cost for hardware.

"All devices should have all capabilities built in from the beginning," Lurie said.

A big step toward universal connectivity could come this year, as major U.S. carriers are gearing up to offer new data plans that can be shared across multiple devices. For example, a user could pay for one AT&T data plan, and have their allotment available via both an iPhone and an iPad.

AT&T mobile business CEO Ralph de la Vega told CNet this week that his company intends to offer a "family data plan" in the near future, allowing consumers to buy an allotment of data that can be used by multiple devices. Though de la Vega said he's "comfortable" with the plan AT&T will offer to its customers, he declined to give any specifics as to how it will work or what the pricing model will be.

Another barrier that remains is the price of radios: Cellular HSPA+ radios compatible with AT&T's 3G network now cost about $30 on average. But 4G LTE radios, like the ones found in Apple's new iPad, are still as high as $70.