The architect of the policy, Lord Sutherland, said "there are no sacred cows" for public spending cuts.
A report for Age Scotland, which Lord Sutherland helped launch in Edinburgh today, claimed a "one-size-fits-all" policy for older people's services will become increasingly hard to justify as budgets are cut.
The consequences of the economic crisis and looming spending cuts will be "quite awful" for some people, Lord Sutherland said.
"This means, in my view, there are no sacred cows. If you're talking where we have to trim, it's very important that we don't isolate so many things as beyond consideration that everything else gets cut to death."
The report, carried out by Edinburgh University on behalf of Age Scotland, looks at the impact of public policy on older people since devolution.
It asks if over-65s from all income groups having equal access to free personal and nursing care is justifiable.
It also questions why even the wealthiest over-60s get concessionary bus travel.
"Universalism versus targeting or means testing is likely to take on a higher profile as public sector resources become squeezed following the recession," the report said.
The Tory-Lib Dem UK Government has announced 6 billion of public sector cuts for this year alone and is planning more to follow.
Lord Sutherland said blanket cuts are the "wrong way" to approach the
"You do have to look at what the priorities are and where there are important matters. You have to have some sort of protection," he said.
"I don't think the health service should be sacrosanct because I think we can't afford the health service we've got, not in the current position.
"I don't think we can afford the foreign policy and defence policy we've got."
The peer called for greater integration of health and social care budgets and claimed that where this happens locally, the quality of care improves.
David Manion, chief executive of Age Scotland, said: "This thought-provoking report raises issues that, to date, there has not really been a need to address.
"In so doing, it makes an important contribution to the debate surrounding the future of Scotland's groundbreaking older people's policies and seriously questions what the future should hold for the next generation of older Scots."
Free care for older people was implemented in 2002 by the Labour/Lib Dem Executive in light of a royal commission chaired by Lord Sutherland. It is a key policy of the SNP administration.
Two years ago spending watchdog Audit Scotland said it had an annual funding shortfall of 63 million, which it expected to increase.
The SNP Government has agreed to increase funding to councils by 40 million after financial concerns were raised in a review by Lord Sutherland.