Is the worldwide race to keep expanding mobile bandwidth a fool's errand? Could maximum data speeds—on mobile devices, at home, at work—be approaching "fast enough" for most people for most purposes? These heretical questions are worth asking, because industry bandwidth tracking data has lately been revealing something surprising: Terrestrial and mobile-data growth is slowing down. In fact, absent a dramatic change in consumer tech and broadband usage patterns, data-rate demand appears set to top out below 1 billion bits per second (1 gigabit per second) in just a few years. This is a big deal. A presumption of endless growth in wireless and terrestrial broadband data rates has for decades been a key driver behind telecom research funding. To keep telecom's R&D engine rooms revving, research teams around the world have innovated a seemingly endless succession of technologies to expand bandwidth rates, such as 2G's move to digital cell networks, 3G's enhanced data-transfer capabilities, and 5G's low-latency wireless connectivity. Yet present-day consumer usage appears set to throw a spanner in the works. Typical real-world 5G data rates today achieve up to 500 megabits per second for download speeds (and less for uploads). And some initial studies suggest 6G networks could one day supply data at 100 Gb/s. But the demand side of the equation suggests a very different situation. Mainstream consumer applications requiring more than 1 Gb/s border on the nonexistent. This is in part because mobile applications that need more than 15 to 20 Mb/s are rare, while mainstream consumer applications requiring more than 1 Gb/s border on the nonexistent. At most, meeting the demand for multiple simultaneous active applications and users requires hundreds of Mb/s range. To date, no new consumer technologies have emerged to expand the bandwidth margins much beyond the 1 Gb/s plateau. Yet wireless companies and researchers today still set their sights on a marketplace where…