The smartphones markets in established markets such as North America and Europe have already begun to saturate as even price-sensitive consumers can now afford low-cost smartphones. Even the tablet market’s explosive growth has begun to show signs of slowdown.

As mobile providers begins to run out of new customers to entice with smartphones, they will have to get creative and competitive with both their offerings and marketing. T-Mobile has led the way this year with its “Jump!” pricing plans and more recently by offering unlimited international data service at no extra charge to customers.

All of the major U.S. mobile providers now provide no contract, no subsidy plans similar to T-Mobile’s Jump! plan. Market research firm ABI Research this week predicted that these services and more will be key to mobile providers’ growth in the coming years. The firm believes that carriers will have to offer a broader product range in the coming years, including convertible PCs, and wearable computing devices. Data plans covering a variety of devices on the same plan will also be key for carrier growth in order, says IDC, to drive up revenue coming from each customer instead of luring in new customers.

“U.S. carriers need to ensure they have the right multi-device data plans, billing infrastructure, user analytics and segmentation in place to ensure their use of subsidy is well spent across these new device categories,” said Nick Spencer, senior practice director at ABI. “Insuring that these devices are actually using their networks and services is the first step in driving revenue out of this opportunity.”

ABI believe that the trend toward selling more devices to each consumer will also benefit device manufacturers. The firm cautions, however, that those same manufacturers will have to diversify significantly to keep up with unpredictable industry trends.