So I'm no historian, I believe traditionally the whole family lived together due to lack of money. This happened rurally or in towns. My dad grew up poor and all 8 of them (6 kids) lived in 1 room. Over time kids moved out and the parents transitioned to living with one of the kids, in this case my dad.
My dad did well as a professional and provided for all of us including some spending money for my grandparents. My grandma passed away in her 60s so it wasn't long but my grandad stayed with us until the end, no nursing home or anything. It was great because I got to live with him until the end, seeing him every day.
My grandad spent most of his time going to yumcha, day trading stocks at the stock brokers offices (very common past time for the elderly in HK), playing majong and cooking. It seemed like a pretty good retirement. He lived to his early 80s.
He did retire early by western standards. He was a logistics foreman then a small shopkeeper. The bargain is that he provided for the kids so they then took care of them. Oh also he would have worked longer than most of us, barely finished middle school, definitely no university.
I guess I'm the first generation that has broken this long tradition. My parents don't expect to live with me, but would like to live nearby.