Kamille in zeon is actually super based. I think the games have a really good take on what exactly would happen to him. I can't imagine family standing by and doing nothing when in ZZ he constantly kept trying to get into suits despite mental capabilities being reduced.
I also don't think he would remain on earth forever either. Even if he didn't join zeon I can't imagine him not participating even if like in one of the AUs he becomes a doctor.

Between manga, games, anime, (movie that makes everybody irrelevant ), and the novels I feel like I don't have to give a shit really. I'm going to stick with the games and think that kamille joined zeon, became a doctor maybe a neurologist? And he fucks char silly.
It would be nice to have some content to analyze from the novels/anime but the games are giving me enough content. I'll take the game kamichar where char lavishes kamille and kamille is bothered by it but doesn't say anything and acts tsundere to him.