With regard to retirement age, it's already late 60s and going up all the time. With or without kids, I still expect to be working until I'm 70. Which I fair enough. As life expectancy goes up, so will retirement age. That's to be expected.
I find it odd, the idea that I should consider my health once my children have grown up, or ability to look after future grandchildren as a factor. My father started to experience severe health problems in his early 60s. I was in my 20s. I was living at the other end of the country at the time, moved abroad shortly after and have lived abroad for most of the time since then. I did ask at the time I originally moved abroad if it was OK, with him being ill, and he said of course he wanted me to go and take the opportunity. My parents have always been big on fostering independence in their kids as well as maintaining their own and wouldn't have wanted me hanging around being in their way, illness or no illness.
Similarly, DH's parents both have a lot of mobility problems but it doesn't affect us. We live in a different country, and they both manage quite independently. They both also have younger partners, but then so do I. We have no expectation of them doing any childcare, in the way they did for older grandchildren, which is partly due to their declining health and partly due to the distance, but the point is, we will look after our own children expect that if our kids have them, they will look after theirs. We both grew up not knowing some of our grandparents. This idea of a close extended family is just a bit alien to me tbh. It's not something I've ever experienced, nor would want to. I'd find it sniffling.
So fine, I may not be (but may be) an active grandmother. Would anyone seriously say that was a reason not to become a mother? Our child will have several different citizenships and will probably live in several different countries during their childhood. Maybe, once they finish their education, they will live close by, but I hope they go off and experience as much of the world as possible. If they wound up living down the street from me I'd be disappointed for them, tbh.