Those are great questions.
I do know several families where the Grandparent is supporting the entire younger generations. They live in modest homes with a combination of support from the Grand parent and the Government.
When the Grandparent passes on they will be in big trouble.
often we older people are in jobs that we have seniority, and are at the top wage level....maybe it makes sense for grandpa to keep working...
but everyone must contribute something....do odd jobs for cash...not spend...cook at home..etc...