The capital could see a population of 2.35 million by 2040
A new report from the Economic and Social Research Institute (ESRI) says the development of second-tier cities is key to sustainable growth.
It says if the current pattern of growth continues, it will lead to "a further gap in prosperity" between Dublin and the rest of the country.
In Dublin, it says this will lead to additional housing demand and increased long-distance commuting.
The ESRI says: "Policies should aim to re-balance growth by encouraging regional development led by a small number of large urban centres outside Dublin".
The research gives projections for regions and counties across Ireland up to the year 2040 - examining what will happen if current planning patterns continue, and what would happen in a range of alternative scenarios.
The projections show that if current trends continue, population growth, employment growth and jobs growth will be concentrated in Dublin and the mid-east of Ireland.
Population growth will be greatest in and around the major cities, particularly Dublin.
The share of population in the Dublin and mid-east region will grow from 40% to 41.7% by 2040. This means the population here will increase from 1.91 million in 2016 to 2.35 million in 2040.
The ESRI says above average employment growth is projected for the mid-east - of 1.6% annually - and to a lesser extent in the south-west (1.5%), west (1.5%) and border (1.4%) regions.
Dublin and the mid-east are projected to have above-average growth in the number of jobs available, at 1.7% annually.
The research finds that the most positive outcomes would be from a scenario in which growth is split equally between the east and midland region and the rest of the country.
"This would relieve pressure in the Dublin region, while still allowing significant growth", it says.
"Scaling up second-tier cities would provide a greater range of functions in surrounding areas."
To achieve this, it says infrastructure needs to develop within the cities - such as water and wastewater, urban public transport and schools.
It also notes that affordable housing and other amenities "is essential" in order to attract people to live there and to avoid further sprawl.
"The increased scale of the second-tier cities would allow them and their wider hinterland to generate more start-up firms and attract more FDI", it says.
Edgar Morgenroth of the ESRI says: "When economic activity is concentrated in one centre, national economic performance is reduced.
"The lack of scale of the second-tier cities in Ireland reinforces the dominance of Dublin and limits the development potential of the other regions.
"Investing in second-tier cities is essential to ensure sustainable economic growth outside of Dublin."