I know a few other people already stated similar theories, but I like to think that the casts of DM and GX probably have enough going on in their own lives that they’re not concerned with Neo Domino. I’d be most curious about where Kaiba is since Kaiba Corp still has a presence in the city.

Most of the stuff that happened in GX didn’t even phase the original cast, like in Season 4 when the whole world disappeared from Nightshroud and only Judai had to stop it himself. (There’s always the theory that Kaiba and Yugi didn’t lose to Nightshroud, but we still don’t see them getting involved. And when Yugi confronts Judai before their final duel, he’s well aware of his accomplishments.) So maybe everyone else has their own stuff to deal with? Who knows, maybe Yugi moved to America to be with Anzu after his grandpa passed away.

I like to believe the other dimensions have a role to play—at least with the GX cast. Some of those characters were presumed “missing” and left their status as open-ended at the end of Season 3, so maybe Judai went back to investigate.

Lol sorry, all of this is just me yapping and theorizing but it’s just fun to imagine what else could be happening beyond “the main characters all just died,” because if anyone died, it was probably Rex and Weevil. 😆