Napping Princess, Sister New Devil and Space Dandy have appeared in the sale though (albeit as SE or DVD sets) so would they still count?
Your Name steelbook also appeared in the mid year mystery box so that one is dubious as well, I could be completely wrong though
Jokes aside. Mystery Box for Blu-rays are collector's edition exclusive and I see no reason why they can't include them since not everyone is going to go for a standard. Plus given they have 10 titles to fill, had the line-up be strictly "can't include a title because a DVD or BD standard was in the previous sale" it would eventually make the list too obvious.
There's also the factor that some of the titles I listed are technically under "almost out of print" territory so this year's line-up is going to be interesting.
There's also the factor that some of the titles I listed are technically under "almost out of print" territory so this year's line-up is going to be interesting.