I am very curious as to what they're going to do with VRAINS as a significant portion of their characters still have decks that are anime-only. They'll probably be alright for the first year, but once they hit season 2 it'll be interesting to see what they end up doing.
The only anime-exclusive cards in Duel Links are ones that appeared in previous video games, so I doubt we'll get any Vrains ones. That being said, there's a decent number of characters we already have that didn't use many (or any for a couple) cards, and they've managed to choose stuff to give them just fine.
Yeah, by next year they would need to release a pack in OCG/TCG solely for Vrains archetype.
And if they're willing to make the pack bigger, they can include new support for decks in Zexal and Arc-V. There are a couple decks from those series whose user are not in DL yet, but all their cards are already in DL. So now the only way the users can be put into DL, is if they get new cards first.
Axel had unreleased cards. Scattershot and Counter to name a few. That's why he's not "the perfect counterexample", because he had cards that can come with him.