Some rumors about AA6 from /v/. It's from 4chan of course so take it with a massive grain of salt, but the guy seems reputable and the info itself isn't all that outlandish.
-AA6 will be revealed at TGS, hoping for an April 2015 release.
-They want to do a Worldwide release as well. They're upset about AA5 spoilers getting leaked before the English release.
-Capcom is happy about AA5's sucess Overseas. Will probably be Digital only and $30 again, but nothing is set in stone.
-The three character dynamic returns.
-5 Cases. 1/4/5 are connected while 2/3 is the usual stuff.
-Dual Destinies is intended to be the start of a new trilogy
-AA6 will cover some of the stuff not explained in AA5
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from AJ will be an extremely important plotpoint.
-They're aiming for the mysteries to be a bit more serious, taking inspiration from police fiction like The Wire.
-Edgeworth, Trucy, and Pearl are returning.
-Ema and Gumshoe are the main detectives of the game. When they talk together a mix of both their themes is played. They're always in two-sided rooms and their music will switch to their respective themes one talking to one or the other.
Here's a screencap of the posts. There's some Apollo Justice and Dual Destinies spoilers, however.
http://i.imgur.com/vvN5LQk.png