I wonder about that though. I happen to be a rather enthusiastic smash player so naturally when I heard Amazon had the upcoming one up for preorder I jumped on it. There isn't actually any announced date for it, the only official word was that it would come out this year (2018). Amazon put a date of December 31st which is pretty obviously just a placeholder date. I don't think this has much to do with any scheduled release date so much as perhaps since it's technically an already released product they just don't consider it a preorder. I'm also not sure if they previously HAD some stock of it or not though I feel like I've seen them do this before.