Update (October 11th): An FCC spokesperson has gotten in touch with us to clarify this situation a bit. Phones won't specifically be required to have GPS, but they will eventually be required to meet the more stringent location accuracy standards previously laid out by the agency either through a handset-based solution or a network-based solution (or a combination of both). The date for that requirement is yet to be determined, but it won't be before 2019. Its statement is as follows:
The FCC is not requiring that all mobiles be equipped with GPS in 2018 for purposes of providing E911. Rather, not before 2019, on a date still to be determined, carriers will have to meet the more stringent location accuracy standards that now apply to those carriers using a handset solution for E911, and they may choose which solution to use: handset-based (meaning a GPS-type chip in the phone), network-based (meaning through network software and equipment), or a hybrid (which is how the technology seems to be evolving).