Greater Boston could stagnate and become a far less vibrant area over the next few decades, choked by restrictive housing policies that help drive away restless young people and leave behind a rapidly aging population.
Or it could boom, driven by a surge of young adults drawn by affordable housing and the appeal of urban areas that offer exciting cultural and entertainment options, top-notch colleges, and smart transit choices.
These competing visions were laid out in a report released this month by the Metropolitan Area Planning Council. Which scenario plays out, planners say, depends on housing and transportation decisions that are being debated in many cities and towns right now.
“If we don’t have the housing we need, we can’t attract the people we need, and it discourages employers from moving to the region,” said Marc Draisen, executive director of the Planning Council.
If there is strong growth, a large number of communities would see their population expand, some substantially, according to the report. Boston’s population could shoot from 617,000 in 2010 to more than 700,000 in 2030, with nearby urban areas also expecting growth.
In the Globe South area, Cohasset, Raynham, Abington, Middleborough, Braintree, and Quincy could see population growth of more than 15 percent by the year 2030. But Hull, Scituate, and Rockland are projected to lose population.
The region will see strong growth if it can build enough housing, particularly apartments and condos in urban areas and town centers, if it can attract and retain more young people, and if the trend toward urban living continues, according to the report.
On the other hand, “continued widespread opposition to new housing” will likely result in less growth, the report’s authors said.
The Boston metro area, which the report defined as about 160 communities roughly within the Interstate 495 belt, could grow more than 12 percent to about 5 million residents by 2040, if there is strong growth — or by about 6 percent, if growth is slow.
Draisen pointed out that the numbers are simply projections. Communities could grow or shrink at rates not predicted because of policies and decisions taken by local officials or other changes not accounted for in the report.
Braintree is already focused on bringing more housing to its centers, said Mayor Joseph C. Sullivan. “We’re focused on our local squares,” he said.
He pointed to a 16- to 20-unit apartment building proposed for South Braintree, which is a short walk to the Red Line; a possible 116-unit apartment building, with retail on the first floor, at the Landing, next to the Greenbush Line; and several other projects as well.
“There’s 200 units of apartments or condos that are planned to come online in walkable areas over the course of the next 18 months,” he said. Plus, school enrollment is growing, which creates its own problems, but is a good sign for the community, he added.
“Quincy is definitely trying to do the right thing, with very good planning,” Draisen said. While the massive Quincy Center development gets the most attention, the city has also worked hard to encourage development along Red Line stops.
Quincy Mayor Thomas P. Koch said there are 500 apartments and condos permitted to begin work by the spring and another 1,000 to 1,300 in the pipeline. Most of the building boom is geared toward housing for young professionals rather than families. That helps the tax base, without putting a strain on city infrastructure, such as schools.
As one example of smart growth, he pointed to 22 apartments approved for a “sliver of land” near one of the city’s four Red Line stops. “They are smaller units, but that is what the market is calling for,” he said.
The Boston metro area faces staggering demographic changes during the next few decades as millions of members of the baby boom generation retire, said Draisen. Younger people will be needed to take those retirees’ places in the workforce to help the region grow, he said.
Housing is key, said Draisen. Employers want to start companies in the area and employees want to live here, but housing prices are so high it is difficult to find anything affordable. Especially needed are affordable homes in urban areas and around town centers, whether they are apartments, condos, or single-family houses built on small lots.
The report says about 435,000 units of housing will be needed, mostly in urban areas and mostly apartments and condos, for both young people and older people moving out of single-family homes.
Younger people are far more interested in living in areas where work and entertainment are close at hand, even within walking distance — a much different attitude from that in the 1960s and 1970s, when homes were built far from work, Draisen said. Increasingly, people hear the term “bedroom community” as a negative, a reversal from a generation ago.
He does see communities where officials understand this, mentioning Boston, Cambridge, Somerville, Chelsea, Salem, Quincy, Malden, Melrose, and Natick.
It doesn’t have to be just the big cities that grow, he said. Young people want to be in town centers where there is good mass transit and entertainment, “where there’s vibrancy and lots of things going on.” They don’t mind having a car, but don’t want to drive everywhere.
He is optimistic about growth, but change can be difficult. Town officials may understand what needs to be done, but “the gap between understanding and zoning, that will be a big challenge.”
Many developers still find themselves tied in knots over projects that should be allowed to move forward quickly, Draisen said. Communities need to be more proactive and allow more building in the right places. The region now builds about 8,000 units a year; that should be as high as 14,000 to meet future needs, he said.
Barry Bluestone, director of the Dukakis Center for Urban and Regional Policy at Northeastern University, praised the report as showing a path forward for area communities. And he echoed the report, noting that its conclusions are only projections and communities can make changes to shape their future.
The three most important issues are affordable housing that’s appropriate for young people, such as apartments and condos in city or village centers; good schools; and fun, interesting amenities such as good restaurants and parks. Mass transit is also needed, he said.
“Demographics are not destiny,” he said. “They can change their destiny.”
But if changes are not made, the metro area could become much older and less vital, he noted. What is needed, Bluestone said, is “putting in place programs and policies that allow the region to grow faster and retain and attract younger people.”Matt Carroll can be reached at email@example.com. Follow him @globemattc.