Bloomberg's most recent report on Apple and its next-generation modem woes suggest that the company is in even more trouble than previously imagined. Its choices for 5G hardware in future iPhones are apparently limited and come with compromises. Therefore, it JUST may skip this feature in 2020 as well as 2019.
https://www.notebookcheck.net/Apple-s-first-5G-iPhone-may-end-up-even-more-delayed-than-currently-thought.413226.0.html