http://neweva.blog103.fc2.com/blog-entry-2391.html
Too pressed for time to translate things in full, so Article summary follows:
Article Summary wrote:On page 138 in last month's edition (July 2013) of the magazine Otona Famitsu, an article blurb about the 3.33 BD/DVD (as well as the success of 1.11 and 2.22) comments on Final getting a Winter 2015 release--along with trailer recording being a hot topic.
Then page 139 of this month's Otona Famitsu (August 2013) has a chart of films planned to be released in 2015 which includes Final.
Minna no Eva Fan mentions how this speculation meshes with the Internet, a Japanese Yahoo Answers page: Somebody asked if the 3.33 BD/DVD has bonus footage that includes the supposed release date, but the image found online (said preview/tel-op image is in the Minna no Eva Fan article) is obviously fake.
Presently, Final's theatrical debut isn't fixed but it's good to think about.
EDIT:
There's another rumor mentioning a 2014 release according to Google search: http://neweva.blog103.fc2.com/blog-entry-2325.html
July 1st 2012 is when Q's release date was given, so maybe they'll be something similar this year for Final.
FWIW, illustrator Yoichi Fukano (深野洋一) seems to think Final will be released in 2015, though I doubt an illustrator has any insider knowledge. (Unless they're one of the higher ups.)