I remember visiting for the first time my great grandmother when I was 6 years old. She was 99. When she saw her great grandson topless with shorts (hey it was the tropics) she reached forward and gave me a massive purple nurple and laughed. She was still shopping daily and moving around.
So I'm not really sure what scare mongering tactics in favour of parenting you are trying to propagate here.
Don't have kids just because you are expecting them to take care of you in old age. That's just cruel.
Here is a better reason: You'll be dead quite soon in any case, so unless you're in agony, you may as well enjoy your final days here. Think of some of your favorite activities and pick one. Rinse and repeat.
Sound shallow? Maybe, but I've spent an awful lot of time contemplating the question.
In the future when people have real options this is less likely to be an issue.
Also neither is yourself getting children or other people getting some a guarantee for a dignified existence in a future nursery home nor is such utilitarian thinking a good basis for deciding on whether or not to bring someone into the world.
Humans will eventually go the way of the Dodo - and that's okay. Because we are not special. Not at all.