Pauline Ford, the RCN's adviser on the elderly, said: 'Local authorities running out of money for care in the community are likely to cut home help and meals on wheels. This will leave the old abandoned in the privacy of their own homes.'
Cuts in community support services are likely to take place in some local authorities within months, the RCN believes. The pressure will then shift to relatives because hard-up councils will be unable to afford to put the people affected into residential homes.
Many families are now finding that the capital they could have expected to inherit from their parents is more likely to be swallowed up in nursing costs, while others find they must subsidise their relatives' care once the money has run out.
The problem was highlighted earlier this week when the British Medical Association pledged to investigate evidence that families were 'granny-dumping' - refusing to take elderly relatives home from hospital, insisting they could not care for them or afford nursing fees.
Hospitals were increasingly unable to discharge such patients because they had nowhere to go, Dr Alisdair Riddell, chairman of the BMA's community care working party, said.
In Britain and America, some families have gone to the extreme of dumping confused relatives at hospital casualty departments or community centres.
It is a far cry from predictions two years ago in the Economist that 'more and more lucky people will be able to plan their retirement around the cash their parents leave them'.
Dorothy White, of the Relatives' Association, said: 'Relatives think pounds 100,000 savings are a lot of money and can't imagine their 92-year-old mother living very long. But people do live a long time in a home where they are well fed and looked after and not stressed.'
As a result, families are forced to subsidise relatives when the money runs out if, as is often the case, the weekly rates are above government limits.
In the South-east, it can be impossible to find nursing home places for less than pounds 280 a week ( pounds 315 within Greater London) - the maximum the state will contribute - or residential homes costing less than the state ceiling of pounds 215 a week ( pounds 240 in London).
Changes in social security rules have also increased pressure on family carers because the Government no longer recognises the right of the elderly to residential care.
Families could now be forced to continue to look after an elderly relative against their will if, following changes on 1 April, an assessor does not agree that the relative needs residential care, according to the Carers' National Association. In that situation, the local authority would not pay the fees.
Pressures on carers have intensified with the widespread closure of NHS care beds for the elderly and significant cuts in respite hospital beds to give carers a break.
'Headlines about granny- dumping give the impression relatives are very selfish,' Mrs White said. 'The vast majority are not. People ring me and say they thought they could cope looking after their mother, but she has gone downhill and is interfering in everything.
'The husband is saying 'It's her or me' and the children are reluctant to come home. In that situation, people find it very difficult to know what to do.'