Scottish colleges and universities are sitting on a population time bomb, education expert John Field has warned.
Professor Field, director of Stirling University's Division of Academic Innovation and Continuing Education, said government figures showed that Scotland was the only part of the UK set to suffer a substantial fall in population over the next two decades.
The number of 17-year-olds - the age at which many Scots go into further or higher education - is predicted to fall by more than a tenth over the next ten years and by a quarter over the next 20.
"Assuming that half of all 17-year-olds enter higher education, the fall over the next 20 years will be about 8,500 Scottish students," Professor Field said.
A Scottish Executive spokesman said: "We are already very clear about the challenges Scotland faces from population decline and demographic change.
That is why we are acting now to attract fresh talent from overseas as well as encouraging our home-grown talent to succeed."
The Fresh Talent initiative, established to attract inward migration, included visa extensions for overseas students to enable them to stay in Scotland after graduation for up to two years, and funding to support universities in coordinating the recruitment of overseas students, he said.
A spokesperson for Universities Scotland said Scottish institutions faced a great deal of competition, but there was no sign of any recruitment difficulties in the near future.
"If the population is going to decline, it is even more important to ensure that the workforce has high skills," he said. "If the Fresh Talent initiative achieves what it has set out to achieve, then it is hoped that we will be able to bring many new people into Scotland to study."
But Professor Field said Fresh Talent would have to expand with "serious resources" behind it if it were to meet the shortfall. He warned that, because of the gradual population decline, institutions risked a fate similar to that of a frog being boiled to death in a pan because the water is heated up slowly.
"Universities and colleges will find themselves having to compete with employers to attract able school leavers," he said.
Much more further and higher education would have to be taken part time in combination with work and family commitments, Professor Field warned.
"The implication is that there will be more work-based and workplace learning, and possibly more so-called blended learning, with face-to-face and online learning," he said. "Universities that already recruit a lot of part-time and mature students will probably find things don't change very much, but universities concentrating on 17-year-olds will find things getting difficult over time."
The Scottish Executive said the changes had been recognised in many of the Government's policy statements.
"The Framework for Higher Education in Scotland encourages higher education institutions to be creative and innovative and to develop new options for degree-level study, including accelerated and intensive courses, full-time, part-time and mixed provision," it said.