You might slightly misunderstand what 5G is because all everybody talks is mm Waves.

5G spectrum covers low-band and-mid band spectrum from 1G through 4G LTE frequencies. Then there is this new high-band. First 5G installations are deployed into new high-band.

5G installations in countryside will be low band that is more efficient than 4G/LTE. You can have _less_ base stations than LTE, not more in the low-band. 5G NR is more efficient radio interface in all bandwidths.