Speaking of poster boy, and I know you aren't suggesting it should be considered, but Sam cane is about the worst poster boy we could have. He's the most stereotypical simple white rural person you will find in New Zealand, and will only serve to keep that section of all blacks support which has remained loyal over the last 25 years, during which time there has been some major loss or shifting of loyalties amongst other subcultures. Educated white city boys and girls Are no longer particularly interested in rugby, Especially left wing leaning ones, small town Maori still have some interest but their level of passion has diminished, many Aucklanders, Polynesian and white, have shifted allegiance to league.
rugby being seen as the rich white boys game, governed by them, coached, captained, and all looking after their own, doesn't help keep the rugby culture strong.
I'm not saying there was any great alternatives though, except maybe a co-captain idea could have helped push the view that the all blacks represent multi-cultural New Zealand.
Ideally there would be a public figure in rugby representing the educated left wing. Tj is probably the closest we have; he is outspoken about gay rights and mental health, as are Ardie, Brad Weber, and Anton Lienert-Brown brown. But they need to be more public than they currently are, so the fringe supporters see it. Tj is also outspoken about educating himself, for example in learning the te reo Maori. We can't really expect rugby players to be tertiary educated these days as they are playing rugby instead of getting tertiary qualifications.
ideally there would be a public figure in rugby representing Polynesians. Who are the next Polynesian superstars? We have Ardie, the rest are quiet humble types. They probably need a bigger voice.
what about Maori? There are No true, immersed in the culture, Maori in the all blacks at the moment. Tj is probably the best here because, while he has felt like a "plastic" Maori, he outwardly respects the Maori culture and is trying to learn more about it.
so, on pure poster boy status, tj and Ardie could be co-captains. Maybe Ardie starts as captain, tj comes off the bench and becomes the new captain.
now, back to your point of requiring the captain to have the respect of the players, I think tj has, but isn't first choice starter. Maybe he could have been a co-captain with Sam Whitelock, and Ardie brought into the leadership group for an apprenticeship. 2 years later Whitelock steps down, with Ardie moving into a co-captain role. Or, Sam cane as captain, Ardie and tj as official vice captains.