Don’t worry about it, my in laws were in there 90s when they died, enjoy what you have and stop worrying about what might be in the future. Anyway your DH might not die first...............?
Enjoy your husband while you still can. Join National Women's Register and make new friends in your area. I live alone, see my surviving AC and family regularly, but I'm not dependent on them for day to day support. Families are busy people. Mine are always there for me, but it's so important to have friends of a similar age to laugh and sometimes to cry with.
A close friend is a widow and a few years old than I . I think as I am about to come up to a zero birthday and pondering the future. If my husband was to pass first I realised I would be quite alone. Couple of amazing girlfriends , my son (not estranged nothing like that ) talks WhatsApp when I post a comment. We see them every three weeks a couple of hours . They are much closer to my daughter in law's family. Just pondering how life could be .