It looks like I probably won't end up having children - mostly due to chronic health issues that I won't get into here. I'm working through the sadness of it, part of which is (not sure if healthy or not?) hoping to have a great relationship with my niece, who is currently a baby, as she gets older. I live pretty close to my DB and DSIL, and likely will for the forseeable future, and see her on a weekly basis. But she's still only one, so true "bonding" opportunities are obviously still limited! But I do hope we'll develop a great bond when she's a bit older. I know it's not the same as having a child of my own, but knowing I'll have something of an opportunity to be a close adult in a child's life is helping a bit. But in reality, I imagine this will depend on a lot of things; how she develops, her personality, whether or not she actually likes me(!), and how my relationship with my brother might change and evolve etc.
Just curious to hear any nice accounts of people who are either childless/childfree, or even people who day have their own children, who have genuinely close, affectionate relationships with nieces/nephews.