That is tough if you don't have a spouse or children. I have very little family but I am married with adult DCs (who are currently not living at home full time).
I do get lonely sometimes esp around the times people have big gatherings, although we do have DH's family for Xmas it's just his DB, his wife (no comment!) and their DCs if about (also adults). All our parents have now passed but the generation below us haven't had children yet so it's small.
Would you think about going in to retirement accommodation when you reach a certain age? I've recently been visiting a family friend in hers and it is such a lovely community - I'd definitely consider it if DH dies first - I'd rather live in a smaller flat and have the social side, than rattle around in a house on my own and be lonely.