Players have had a lot of time to remove their items from either Auction House. Blizzard has done a very effective job of making it clear that the Auction Houses are about to close. They posted it on the log in screen for Diablo III many times. Several different Blizzard Twitter accounts have sent out Tweets about it. Even Tyrael (@AspectofWisdom) reminded players about it!
The @Diablo Auction house will be closing tomorrow. Make sure you check the "Completed" tab to make sure of no leftover items!
— Tyrael (@AspectofWisdom) June 23, 2014
Those who had items left in either Auction House got an email a few days ago that reminded them to go get their stuff before it disappeared. The email included instructions about how to go about collecting the items.
Despite all the warnings about the impending closure of both Auction Houses (which Blizzard started sending out in March) there are going to be people will be completely shocked and surprised when they realize sometime tomorrow that can no longer retrieve the items that they left in the Auction House. The items that they ignored, and left to gather virtual dust in the Auction House, suddenly become incredibly meaningful to them. I am expecting a lot of complaining by disgruntled, procrastinating, players all over social media tomorrow.