Ireland now has better 5G coverage than Deutsche Telekom plans for the end of 2021. Putting 5G on existing towers can be done quickly, especially where 4G upgrades are needed. Mid-band 5G has decent reach, similar to 1800 MHz.
At least 60% and often 80% coverage can be reached from existing towers. The Europeans do not expect to deploy many small cells for years. The Chinese don't need new cells for coverage, but have ambitious plans for indoor coverage, perhaps as many as 10 million small cells. That would be enough to put multiple cells inside every office building.
Xavier Niel became a billionaire by giving customers more for their money. The industry thought he would go broke when he offered the 30 Euro triple play but he had carefully calculated marginal costs. Most made a similar mistake when he introduced mobile for 20 euros several years ago. He made that work.
Eir also announced gigabit fiber to 50,000 homes and plans to fiber 84% of Ireland. 38% of Irish live in rural areas, nearly twice as many as England. Rural costs are high but Eir's reaching many in rural areas without any subsidy.
I guess the engineers at BT should go to Dublin for an education.