Outerplaces.com have published the name of the final 5 episodes of the second season of Star Wars Rebels. The last two will be aired as a one hour special and have the omminous name "Twilight of the apprentice."
We know from the previews (read all about it here) that Ahsoka will face Darth Vader. Does this mean she will die? or maybe she, like before, will just leave. Vader will definetly try to kill her. She is the last reminder of his former self. The showdown will apparently happen in a Sith temple, and Ezra will be there too.
By the title we are all assuming that the "Aprentice" in question is Ahsoka. But remember, Ezra is an apprentice, and Kanan basically never actually became a Jedi (just like Ahsoka).
A little more than a month to know the answer.