On December 29th, all eight films are going on moratorium, meaning that copies will no longer be printed and that, after that date, new stores will not be able to reorder more.
The sales move, made famous by Walt Disney Home Video and its routine placement of its animated fare in the "Disney Vault", will certainly pave the way for a re-release somewhere down the line, though no official announcements have been made as to when the Potter films might reappear. Details from the official press release are as follows:
Harry Potter, the #1 motion picture franchise of all time, will soon disappear from shelves, as Warner Bros. stops shipping all Harry Potter theatrical film titles (including Harry Potter and the Deathly Hallows™ – Part 2, and Harry Potter: The Complete 8-Film Collection) as of December 29, 2011 (moratorium does not include digital – Electronic Sell-Through & VOD – or games). The Harry Potter franchise has grossed more than $12.1 billion for Warner Bros. Entertainment – with $7 billion at the worldwide box office for Warner Bros. Pictures and $5.1 billion for Warner Bros. Home Entertainment Group and Warner Bros. Interactive Entertainment.