I couldn't see them going with one boxed set of exclusively Sisters vs something else. I could see them offering a couple different DV style boxed sets, one of them featuring Sisters. If the Rumors are true, and they're going to go with an AoS style "Forces of the Imperium" kind of thing where all Imperial Armies are rolled in to one "Codex" I could see Sisters featuring very strongly into that. GW has been making overtures towards the females for some time now, and I think that making the game a little more girl-friendly will be a noticeable feature of 8th. Bear in mind that, as a publicly traded corporation, that GW is run, in part, by marketing people now.