5G will just end up re-using the current 3G/4G frequency bands for rural coverage the same way 4G is now using the old 900MHz 2G band. Really old telco types will remember this being used for TACS/ETACS, the original analog 1G service.
3G with dual frequency high speed data in the downlink direction would have been enough for the 99% of mobile users who don’t need crazy DL or UL speeds. Not very efficient frequency spectrum or base station power utilisation though, hence the introduction of 4G which is actually a less complex interface than 3G.
With the channel aggregation in both uplink and downlink directions available in 4G, it should be enough for everyone, but the marketing idiots have drank the 5G Kool-Aid that Huawei have been mixing up for the last few years and now the networks are spending more money they don’t have on a service that customers don’t need.