The CSO has modeled population projections from 2011 to 2046. Quote: Under the strongest scenario - maintaining the total fertility at 2.1 over the entire period to 2046 coupled with net inward migration of 30,000 from 2021 onwards (M1F1) - the population is projected to grow by 2.2 million over the 35 years to 6.7 million. Under the more moderate migration assumption of plus 10,000 by 2021 coupled with falling fertility (M2F2), the population is projected to be 5.6 million, while under the most negative scenario (M3F2) the population would fail to increase above 5 million. The difference in population between the highest and lowest outcomes by 2046 is 1.7 million. The strongest scenarios for fertility and inward migration has the population increasing by 2.2 million over these 35 years, while the most negative scenario has the population increasing by only half a million. The "population explosion!" scenario in the OP clearly relies on the strongest scenario coming true, which is a possibility, but by no means a certainty, especially given how vulnerable Ireland has been throughout its history to major economic downturns (which lower fertility and increase emigration).