[grondo4]

>But some else's child will not have to care for them.

Generally it's considered a burden of society to take care of their elderly. Thus 'someone else's child' will have to take care of the childless elderly in some form or another.

[lotsofpulp]

Depends on the ability of the elderly to obtain that labor. They typically have a decent amount of political power, but it is certainly possible for quality of care to decline in the event that the cost of their care rises too high.