Several problems with 4G are being ameliorated by 5G, including congestion and stability with low signal strength. Here in Canada 5G is rolling out on 600Mhz and 3.5GHz so it will ultimately provide more stable connections than 4G, even at the edge of 4G coverage.
Lack of coverage on the countryside in general exists because of the carriers' unwillingness to invest in areas with lower populations because they don't think there'll be much profit there. 4G vs 5G vs 6G is not relevant, all new towers being put up now are probably both 4G and 5G capable (sub-6 at least) anyway.
Let researchers and standards working groups do what they do, they're not the problem, they're just looking at the future and if we fired them we'd still not get more cell towers on the countryside.