You know... Birds really are something.
Person A could raise a bird after they're weaned and, once it matures or even further down the road, it will seek companionship in someone else. Person B could do the exact same, and the bird would forever be loyal to them. Or, so I've read from all these different experiences. Every bird, as I've come to understand, is different. You can't rely on someone else's experience, fully, because it is not identical to yours - and neither are the birds! They are just like any other animal, complete with their own personalities, triggers, motivations, and understandings of things. It's about how they are raised and trained and treated.
I think that a lot of the time, even when people "know what to expect" and have done their research, they still expect too much from their birds. Specifically the larger species of parrots and cockatoos. I don't think that being hand-fed, wild-caught, parent-raised has everything to do with how your relationship with your birds will be or how it could/will change. Nor do I think that they necessarily need to be with a mate (in this instance, I mean a human "mate") in order to be happy once they mature. Sure, they will get hormonal and they will try to act on those instincts, but that will always pass. I do think that the experiences they have will impact their relationship with their owners.
What's more important than trying to guess how your bird will feel about you in the days, months, or years to come is to focus on strengthening the trust you have with it today. Don't take it personal that they don't cling to you every second of their waking hours, and if they do... well, I'm sure you regret not embracing their independence!
I'm sure there are plenty of success stories for birds that were raised from a baby to an adult by the same owner, just like there are plenty of unsuccessful stories about it. To anyone getting a young bird, the advice I'd give is to realize the small window that many young animals have to being socialized to different people, animals, and even places (and desensitized to the situations that come with them). What you do with that time will set them up for the rest of their lives. SOCIALIZE SOCIALIZE SOCIALIZE: expose it to all kinds of possible situations it might face in the future. Think about if something were to happen to you or if you just can't keep it anymore after so many years, would you really want your bird to be a one-person velcro bird then? Think long-term, not about how adorable it is or how much you want to cuddle it. Teach it what is acceptable behavior or not, do not baby it simply because it's cute and sweet. In my experience, any animal that gets babied from a young age turns into a disobedient terror to have around. Or a just plain demanding, disrespectful nuisance that thinks it can get away with anything. Sorry, that was somewhat ranty, but really. You're not doing your animal(s) any favors by coddling and sheltering them. I'm not saying be cruel or anything, but don't be a pushover either.
Disclaimer: I say "I think..." a lot, because everything is simply my own opinion formed from my own experiences and research. Take it with a grain of salt ^-^