First and foremost, congratulations to @fucho80 and his wife on the upcoming birth of their baby.
I don't view raising children as an investment but as an act of love.
As for whether children will be there to take care of their parents in the future, I think that depends on how they were raised. If they are raised in a family where people act out of love to help and care for family members, they most likely will. If they are raised in a family that views having to take care of elderly family members as a burden and they complain about it, more than likely they won't be there to help.
I know my son grew up seeing Bob and I care for my inlaws. At a young age, he started doing small things to help them out without being asked. He was also there when I was caring for my husband when he was dying. Again DJ voluntarily stepped to help by doing what he could. DJ was 16 when his Dad died.
Since that time he has been there for my Mom, who past away in April. He has a very close relationship with my Dad and offers to help out when he sees something he can do. He acts out of love and not a sense of duty. He has grown up to be a kind, loving, and compassionate gentleman.