The number of older people needing informal care will outstrip the number of family members able to provide it as early as 2017, a think tank has claimed.
The IPPR said the gap of those without adult children to care for them will rise to more than a million by 2030, in research on the rising costs of care.
The report shows the average annual cost for an older person who pays for a typical package of care has increased to £7,900 a year, an average £25,000 for home care and an average £36,000 for a nursing home.
IPPR senior research fellow Clare McNeil said: "The supply of unpaid care to older people with support needs by their adult children will not keep pace with future demand. Thousands of people in their 60s and 70s today could be left to cope on their own when they need care in the future, with overstretched services unable to make up the shortfall.
"Britain needs to build new community institutions capable of sustaining us through the changes ahead and to adapt the social structures already in place, such as family and care, public services, the workplace and neighbourhoods."
The think tank argued there are good examples in Germany, Japan and Australia which could be followed. These show in the absence of adult children, properly constructed neighbourhoods can help other family members, friends and neighbours help meet care needs.
It highlighted a plan by the German federal government, which is investing in more than 500 "multi-generational homes" which bring together isolated groups like mothers and baby groups, childcare, youth groups and care for the elderly under one roof.
It also pointed to a scheme in Leeds, where neighbourhood networks run by older people cover the whole metropolitan area around the city.
The new report is part of wider IPPR research into social policy called the Condition of Britain. A final report will be published in June.