I'm still kinda hoping Ahsoka gets frozen in carbonite and hidden away long to be defrosted in time for Episode VII...
Seriously though, I'd be disappointed if they choose to just have Vader end up hunting her down and killing her. The way they left it with her leaving the order really leaves the door open to some interesting opportunities. There are (I assume) plenty of familiar faces that survived Order 66 who could pop up and face off against Vader.
That's assuming of course he even features. We don't even know yet what the focus of the story might be. Sure, the title certainly means it's something to do with the Rebel Alliance, but that doesn't necessarily mean it'll be about the big players.
Given that they'll be marketing this to kids and one assumes it'll be an action show, my bet is that the main character will be someone new and it'll focus on Rebel fighter pilots. Think the Rogue Squadron books, but with a younger cast...and not actually being about Rogue Squadron.