Apple designing their own modems
Apple is a company that likes exclusivity in all aspects of their business. This is why they have, for example, exclusively employed Qualcomm to produce modems form them - later this exclusivity shrank down to 50-50 share with Inter. Finally, this exclusivity was completely transferred to Intel, which resulted in an all out legal war between the two comapnies, Apple and Qualcomm.
Obviously, such law suits are only hurting Apple, and naturally they wish to mitigate such possibilities, which is why they are now working on their own modem, just as they have already produced their own CPU and GPU. However, this is still just a plan. It is not easy to design and manufacture such a chip, and probably the development may take several years. An educated guess is that we may see Apple made modems in iPhone as early as 2020, but more probably in 2021.