At the age of 50 as I am now I could be quite happy living out my days single. The freedom to do what I want when I want would be amazing. I like the idea of the peace it would bring.
Reality is I am a single parent run ragged and having had my dc late in life I will be well into my 60s before I can do anything I want to do by which time I won't have the energy to do it.
I do enjoy cultural things, the cinema, theatre, reading, socialising so I could fill my life with all that.
I think there are many advantages to being single and childless, I honestly do.
I do miss the intimacy of not being in a relationship though. Also you mention the passion you can feel for someone but how many times in my life have I had that? Only two or three times I think and not in my long term relationships or marriage. The feelings were only for unavailable men so added complications and I daresay if I had had a normal steady live in relationship with them then the feelings would not have been there anyway.
God the thought of living with a man again, no thanks, the compromises, the drudgery, the boredom, sharing the same space, I couldn't do it. But I did want it in my 30s.
When I look around at friends, the ones with the happiest fullest lives are those who are married with no children.