That hasn't been formally announced where, or even implied yet. Besides I was even talking about this scenario. Both systems are getting a game, it's original scenario in which a game was announced for the 3DS more than a year after it's initial 3DS release with a Vita spin that made no hint of this release that, likely would have confused fans.
Especially considering the developer interviews in the periods between.
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http://gematsu.com/2014/01/senran-kagura-estival-versus-playstation-multi-format
Next I'm sure you'll dismiss that as some sort of spinoff, even though Japan doesn't care as the last spinoff is the best selling game in the franchise. Of course now I'm sure you'll bring up the poorly received satellite-only anime, as well as Vita's price cut.