Dwindling numbers of pupils could force some Norfolk schools to close or merge with others, education officials have said.
The warning comes in a new report from Norfolk County Council and follows an analysis suggesting drastically declining local birth rates.
Data shows that between now and 2028, more than 9,000 children a year will move from Norfolk's primary schools into secondary level.
By contrast, in the same period, the year groups entering primary education will number only around 7,500.
Officials believe this may make some primary schools - particularly smaller ones in remote villages - unviable, meaning they will close or merge with others.
It is a scenario that is already unfolding, with one of the region's largest academy trusts looking to merge two village schools, in Weasenham and Brisley.
The falling numbers of children come despite some areas of the county - particularly in suburbs and towns - seeing significant housing growth
The trend will heighten concerns that young families are becoming increasingly shut out from many rural communities, because of a lack of suitable homes, jobs and facilities.
This in turn makes it harder for rural businesses - and schools - to survive and raises fears over the long term future of remote communities.
The process may be accelerated by a new wave of school closures, as young families avoid areas where they face long journeys to get to school.
Penny Carpenter, cabinet member for education at Norfolk County Council said: "The resulting reduction in pupil numbers may not be offset by housing and could impact different organisation structures for schools of differing sizes.
"This may inevitably impact certain schools where the risk of reorganisation or closure may occur.
"We recognise this is always a very difficult decision and we will support schools to explore all other possible solutions first."
Oliver Burwood, chief executive of the Diocese of Norwich Education and Academies Trust (DNEAT) which runs Weasenham school, said: "We have been facing this reality of demographic change, in some areas, for a significant period of time now.
"There are parts of Norfolk where there will be fewer children and in those areas we have already had to make hard decisions and acted to either close or merge schools.
"Weasenham is an example of a school where the pupil population is low, and will fall further, to a point that it is unviable to run."
School leaders fear a wave of rural school closures may leave families with less choice about where their children learn, particularly those who favour smaller schools.
Jonathan Taylor, chief executive of the Sapientia Education Trust, said: "There are a number of factors that contribute towards sustainabilities of small rural primaries and place planning is never an exact science.
"It is important to ensure that parental preference is factored into decision-making - many parents actively choose smaller schools or those with a distinctive ethos.
"Maintaining choice is vital."
GROWING POPULATIONS
In contrast to the falling populations in many areas of the county, some parts are experiencing a boom.
In suburbs and towns like Cringleford, Rackheath and Attleborough - where there are large numbers of homes being built - local schools are becoming oversubscribed.
Earlier this year, council bosses revealed they expect to need to build 26 new schools over the course of the next decade - in areas where the population is expected to swell.
Of these schools, 25 will be primary and one will be secondary - while it is also anticipated that many others will require expansion.
In Cringleford, a new 420-place primary school - Cringleford Prep - is due to open in September 2024.
Norfolk County Council is also working on plans to build two new primaries in Attleborough,Silfield, near Wymondham, and Blofield.
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