That is absolutely your choice, if you are happy and content to do it. But it shouldn’t be your job in life - an expectation as a woman that you do the grind of care work when the time comes. Great if you can do it, and are able to, also fine if your life can’t accommodate such a huge commitment.
It is largely irrelevant if you are a close family or not if you are working full time and have four kids! You are already doing two full time jobs as it is. You simply don’t have the capacity to do more.
Older people need to plan and take care of their own arrangements very early on into older age, so they can have the kind of life they wish for. Whether that’s staying at home and funding home help or living in assisted living etc.
I will never grow old and expect my poor children to pick up the slack for years on end burning themselves out. Dh and I will organise ourselves so we are fully functioning responsible adults, and not a huge burden on our children.
It’s completely unfair to expect other people to give up their lives, career and future to wash my bottom! It’s unthinkable to expect that, totally out of touch with the reality of modern life.
Women work full time now. Maybe in the old days that was not the case and it was easier - life has changed now and yes many more elderly will need to take care of their own needs.