In a way I'd love this.
I would get to treat my dad the way he treated me.
Unfortunately I don't think I have it in me to be that deliberately cruel though.
Anyway, I can see the 'for' side to this argument.
-To help those who brought you up when their time comes to be the ones needing looking after.
-To save on money
-To save on national tax (the little that goes to care of the elderly)
-To assist having a more functional, united society
-To ensure the elderly are not lonely, scared, unwell, vulnerable, easy targets for theft etc...
However it is not even remotely feasible.
(Where I say 'children', I mean the adult children)
-What about when the parents or children are estranged? (ill treatment, ethical issues, feuds, anything really)
-What if the parent left the family home and never knew the child?
-The children would need regular vetting and monitoring to ensure the parent was being cared for properly
-The children may be in a bad financial situation
-The children may have family, work, or other responsibilities that cannot be dropped
-The children may not have sufficient accommodation for the parent
-The child may be physically or mentally unwell or unfit to care for the parent
Oh there's loads more pro's and con's, but it is clear to me that it would never work on a practical level.