Many health professionals believe those with some savings or a small pension are most likely to face difficulties.
For many, the changes could force them to accept cheaper but far less comfortable - even unsafe - care.
The Community Care Act imposes a duty on councils to provide care for the elderly, of which 75 per cent must be bought from the private sector.
The typical cost of a nursing home is pounds 500 a week in London and the South-east, and pounds 375 elsewhere in the UK. A residential home costs between pounds 300 and pounds 375 a week. And the cost of care is rising at more than twice the rate of inflation.
Councils are allowed to apply their own guidelines on the level of help given to those in need. Although the amount paid for nursing care varies, it rarely exceeds pounds 250 a week.
In any case, only those with savings of less than pounds 3,000 receive the full amount a local authority may give. Those with savings above pounds 8,000 will normally get no help from a council at all.
Means-testing may also include the value of a person's home, unless a partner or dependent relative lives there.
Joe Hennessey, director of services for the Muscular Dystrophy Group of Great Britain, said: 'The number of people who, for reason of age or disability, need care and varying degrees of support, will continue to grow. Are the funds going to grow with that need? Not on your nelly] People will increasingly be thrown back on their own resources.'
Jeremy Oakley is marketing director of PPP Lifetime, a health-care company offering long-term disability and protection cover. Over the past two years, the company has been selling policies that allow clients to claim for permanent nursing or other care should they become incapacitated.
He said: 'The importance of similar cover is likely to grow for large numbers of people. Estimates now suggest that the number of pensioners will grow by 50 per cent in the first 30 years of the next century, from about 9 million to more than 14 million. They are also likely to live longer.'
For a monthly premium of pounds 26, a male aged 45 would receive a pounds 200 weekly lifetime benefit should he become incapacitated. Women, who live longer, pay pounds 28 a month. A lump-sum option is also available, whereby a single payment buys the same cover.
Mr Oakley conceded that despite the cover costing much less for younger people, those most attracted by the policies are people over the age of 60.
Among them is Stephen Eastwood, aged 69, and his wife Nancy, of Kettering, who recently took out a PPP Lifetime plan.
Mr Eastwood, a former Crown Court recorder, said: 'I am thinking about my in-laws' own parents. The wife had Alzheimer's Disease, although not for very long.
'Her husband hung on, but eventually had to go on to a home. The house was sold and it was just about enough to provide for him.
'We decided that if anything were to happen to us, we did not want to burden our children with the cost of caring for either of us. We pay about pounds 60 a month and would receive benefits of about pounds 120 a week.'
Another company offering a similar scheme is Commercial Union. Sandy Johnstone, marketing director of its Well-being scheme, said: 'Long-term insurance has very much been based on pure risk.
'If you die or discontinue your premiums you get nothing, which is terrible if you have just paid a large lump sum. What we have done for lump sums is added life assurance for the first five years of the single premium. On regular premiums, we introduce a paid-up value if they have made contributions for at least five years.'
For example, a woman aged 60 may be paying pounds 90 a month for pounds 10,000 of annual cover, rising by 5 per cent each year. If, after 13 years, she can no longer pay her premiums, her policy becomes paid up, but she will now receive pounds 7,400 of annual cover, rising by 5 per cent each year.