Yeah, their effects were too vague and they were ultimately a form of deus ex machina in the anime, which is why I can't see them being printed. And as you said, even if they were made into real cards, their effects would probably be too situational and would make them unplayable, which is what I'm mostly afraid of. I hate it when Konami gives in and prints cards that people want, only for them to be completely unplayable and useless in the end. :x
Personally, I can't imagine any other card being printed that would warrant the title "Dragons of Legend". I don't know any other significant dragons, especially with Seal of Orichalcos being printed. When Seal was announced, people were freaking out, only for seal to get released with toned down, playable effects (Seal is by no means bad, I main one myself in Fire Kings).
I was expecting more of a Legendary Collection 5: Kaibas World release though
So I've been thinking alot about what would happen if these cards were to get released. I feel like Timaeus would be a sort of union monster, giving "x" effect to the equipped monster. Thats what he did for the most part anyway (Dark Magician Girl Dragon Knight Whatever Awesome).
Critias could have a sort of trap protection/retrieval system, perhaps (Its a stretch but I've always loved 'em) making trap monsters SEMI-viable.
Hermos, iirc, involves equip spells. Noble Knights anyone? ;D Or something involving backrow protection in general.
Also (And I highly doubt this but it is TECHNICALLY possible), it could be that with the yugioh decks yugi and kaiba reloaded, they're more character oriented. Though with no Joey (LC04 aside), it's unlikely. Amulet Dragon would become a thing though.
Personally, I'd like to see them come out as spells, since they 'kinda' were anyway. Maybe rituals, like the Eye of Timaeus summons "Atlantean Dragon Timaeus" or something. And the Knight versions would be cool as well. Maybe you do that new Arc react into it or something
There's a whole lot of possibilities, but hopefully they go the Slifer route, and not the Ra route. Even if they smudge the original effect horribly, I still want a fun playable deck involving them. They're one of the card archtypes where I totally understand the need to change them. It was very original-anime-ish, where everything just kinda is because it is. Which is fine, thats why the original was my favorite. But I hope they try if they do release them, and not just kinda half-try.