The new trailer for the finale was posted sometime today. Those who haven't seen it yet can go to starwars.com to find it. Anyway, they briefly discussed it in the Google+ Hangout on Saturday (which can be found on YouTube) but they definitely showed in the trailer that the finale will be a big changing point for Ahsoka From the very beginning that is very clear; the trailer opens with the first scenes of Ahsoka from the Clone Wars movie. For those of you who don't know (SPOILER ALERT) the main plot of the next five episodes is that Ahsoka is framed for a murder and goes on the run to prove her innocence. Anakin is meanwhile also searching for the truth.
There is also a lot more going on in the trailer that shows that there's something much bigger going on than just Ahsoka being framed. There are various sound clips about Anakin having to let go of her and "do what needs to be done". But don't worry, from the Google+ Hangout it didn't sound like Ahsoka was in danger of being killed off (the actress who voice-acts her said that the ending was "so much cooler" than what any fans had speculated). I heard something about Ahsoka becoming Asajj Ventress's apprentice or something like that. That idea isn't completely absurd, because Asajj Ventress does play a role in the arc, but I doubt that it will actually happen. But I think it is safe to assume that next season will definitely not be the same for Ahsoka, whether or not she's still going to be fighting for the Republic.