Rex, Mai, and Weevil all have lines in the game files activating Seal of Orichalchos. It IS coming (especially now that losing access to Extra Deck actually matters in the meta), just a matter of when.
Dartz will never be an unlockable, not enough cards or theme for his drops and level up reward, you can't even make a working lv40 deck with the only 3 cards he have that were printed in real life since none of those 3 directly works with each other.
Valon and Alister are even more unlikely considering their entire decks are anime only, and Valon's cards are so wacky in relation to the real life rulings, that they only works in the anime. They will never show up in DL.
Vector
Anoymous
