First, the interview in question: http://www.cubed3.com/news/5973/1/Capcom
The PW community is in a monsterous tizzy over this. Some believe this is the reason for the gap between Japanese release and domestic, while others believe it's a possible case of misinterpretation.
Myself? I'm being cautiously skeptical about this. Things aren't quite adding up; how are they going to announce new cases so suddenly like this? And how is it that they're going to be western-released specific? Matsukawa herself stated just a month or two ago that there wouldn't be any added content - and I'm sure that if they took the time to develop and implement something so significant as new cases, then surely they'd have gone into the Japanese release as well; it would be a crucial selling point, and something they definitely would've publicized a lot earlier on.
"Brand new episodes" to me sounds like a spiel to someone who's never played Gyakuten Saiban 2 before. As for the "We wanted the Western players to play a new game rather than an old port," I reckon she was referring to the updated features of the DS port, such as touch screen, refined graphics and music.
Not that I'd be adverse to new cases, of course - not in the least. But you can color me surprised if it does turn out to be true. Either way, I'm still picking up both Japanese and domestic releases; and if the domestic release does have new cases, that's all the more reason to double dip. ;)