For the umpteenth time, Rafael is not going to happen, we already have all of his cards. Valon's deck doesn't work outside anime (and especially not in the "3 zones only" format), and Alister's deck is still entirely anime only cards, we don't have Jim Cook (from GX) yet for the same reason. DL is fine with putting a couple anime cards in, but not with an entire deck of it, so far.
Heck, you know what? Yuma's big sister has more chance to be released in DL than Rafael.
At least she has an Evilswarm deck in Tag Force, which does have many cards not released yet in DL. And a rather random deck in World Duel Carnival game, but it still contains cards not in DL yet.
Jim will have his cards in real life soon, of course he can get added.
As for Scud and Lumis/Umbra, again, Lumis & Umbra have unreleased cards, while Scud is a completely blank slate. They have their valid reason for why they can get added.