Enter Intel. At the International Solid-State Circuits Conference In February of 2012, Intel demonstrated and discussed an SoC, called Rosepoint, with an integrated Wi-Fi radio on a chip with two Atom CPUs. That apparently left everyone scratching their heads about how Intel could get a radio to work without RF interference with the CPUs.
On the third day of the Intel Developers Conference in September, 2012, when most attendees are snoozing, Intel demonstrated the Rosepoint chip again, but this time they revealed that the on-chip Wi-Fi radio was actually a completely digital implementation of radio. Digital radio was thought to be an "impossible" technology, but after ten years of work, Intel demonstrated, not pieces, but an entire digital radio transceiver.
The conclusion here is that LTE radio is no more difficult than Wi-Fi radio. If that is true nobody should be surprised if Intel offers a complete digital radio smartphone-on-a-chip SoC within the next year. The size of such a chip would be approximately 50 square mm run on a 14nm process. The manufacturing cost of that chip could be as little #$%$ As we can see from the above bill of materials, the value of that chip to a handset manufacturer might be $35-45.