My Dad died quite young, 62, but was sick for 4 years, ,my mam took care of him and now that she is sick, relies on my young brother to help. I told her to come stay with me but she wont. And I know my sisters wouldn't take her, my mam is hard work and as much as I love her, sometimes I don't like her.
For me, I have no intention of having my kids look after me. If I get dementia/Alzheimer, I hope I have a lucid enough moment to realise it before I get very ill and I would take steps to end it.
Likewise, I wouldn't want to live like my dad did for the 4 years of illness. He went from being an independent strong man to one on 24 hour oxygen, couldn't leave the house, dress or wash himself, it killed him. he had no dignity in death and for that reason, I think I would take preventative measures to ensure no one has to take care of me in that condition.
I know that sounds weird, I have no suicidal thoughts in life, but I would feel very strongly about being a burden on others or losing my dignity and independence.