Europe can support only 30 to 50 top-rank universities, according to David Ward, president of the American Council of Education.
"It takes 5 million taxpayers to support one world-class comprehensive research university," Dr Ward told The Times Higher . "Europe could support between 30 and 50 top-rank comprehensive universities depending on tax levels. The rest will have to diversify their missions. It is unrealistic, for example, for all three universities in a country with 3 million people to aspire to world-class teaching and research in all fields.
"The trend in Europe is towards comprehensive universities aspiring to international prestige or technical schools aspiring to excellence in scientific fields. Many should instead strive for quality in satisfying other educational needs."
Dr Ward was the keynote speaker at a European Universities Association-Association of Commonwealth Universities conference in Turin.
He said that since the proportion of school-leavers entering higher education had risen from 10 per cent to 70-80 per cent in a few decades, most students required higher education for general enrichment and as a basis for lifelong learning.
Not everyone agreed with Dr Ward's analysis. Eric Froment, the EUA president, said: "You cannot divorce universities from research: the quality of teaching inevitably falls. To transmit knowledge, you must be in touch with research. Even a university focusing on lifelong or vocational learning must have teachers involved in research.
"There is hope for everyone. Who can say that Oxford will [remain world-class] for ever? Who can say what the next field of historical progress will be?
"Of course, there are natural pressures on institutions to adopt a role that responds to social needs. Those responsible must realise that not every department in every university can be a world leader."
Rex Nettleford, vice-chancellor of the University of the West Indies, said:
"We must think of universities as a public good, encouraging upward social mobility. And smaller countries must think in terms of niches. In Jamaica, we have departments that are world leaders in fields such as tropical medicine, the economics of developing countries and race relations. And there is a need for strategic alliances in specific fields among universities around the world."
Jean-Marc Rapp, president of the Swiss Rectors Conference, also disagreed with Dr Ward. "Even world-class comprehensive universities such as Harvard have some departments that are better than others. The trend now is for rankings by department rather than by university."