I don't think Oda would've given him that 'copper' name along with Roger and Rayleigh's gold and silver only to totally throw him out of the story. I think there's a 70% chance that he's important and shows up or at least is briefly explored through some future plot.
Last Island before Grand Line and the last island of the East Blue was Loguetown, the last place Roger visited alive, where he was killed, and where Luffy mirrored Roger's laugh while thinking he was about to die.
Last Island before New World and where all the routes of Paradise lead to was Sabaody. There the SH's met Rayleigh, and Rayleigh saw Roger in Luffy.
Last Island before Raftel, the last island that you can reach with a log pose, and where all the routes of the New World lead to is Lodestar.
I think there is where the SH's will meet Gaban, and he will be the last Roger Pirate to acknowledge him as the one Roger said will eventually come. Gaban will also probably meet Blackbeard and make that judgement after seeing both of them.





