When will fixed-wireless access run out of steam?

Fixed wireless access continues to gobble up the vast majority of growth in the US broadband industry. But that trajectory can't last forever. In the first quarter of 2025, the financial analysts at Bernstein calculated that fiber operators in the US collectively gained around 652,000 total customers. But FWA providers (mainly T-Mobile, Verizon and AT&T) collectively edged them out with a total of 703,000 net customer additions during the period. Meanwhile, cable operators lost around 323,000 total customers during the first quarter. But FWA's growth will end eventually because the FWA services provided by T-Mobile, AT&T, and Verizon run through their 5G networks. Those networks must also support most of the 330 million smartphone users in the US, and there's only so much capacity available on 5G networks. That leaves two outstanding questions: How much capacity is left in 5G? And when will FWA run out of steam?