The 5G race has certainly started in earnest in the US, but it remains unclear how the big four mobile operators will reconcile their caution about capex levels in the next few years, with the proposed investment in upgrading their network, arguably before a brand new radio is really justified by new revenue streams. Verizon and AT&T, of course, are initially focusing on fixed wireless, which helps to improve the cost of expanding their broadband footprint, and can help them move out of their fiber footprints. Combined with the lack of requirement to buy early-stage, and expensive, smartphones, that strategy is a sensible way to test new technology, even if it is unlikely to revolutionize their challenged fixed-line businesses. For…