Intel will be able to put an unlimited number of bands on a single LTE modem, possible as soon as late next year. Apple used Intel's modems up until 2010, when it switched over to Qualcomm in part to get Verizon and Sprint LTE compatibility. There is Qualcomm MDM9615 modem is in the Apple iPhone 5.
Modems are only half of the solution, though. Dermot O'Shea, co-founder of antenna firm Taoglas, said antenna design gets difficult when you're covering such a wide range of frequencies. Active antennas for smartphones, which have just started to hit the market this year, can adapt to different bands without being huge, although they add to the cost and complexity of smartphones. We're likely to see more of them next year.