Star Wars Rebels Season4 final speculation: (spoilers from episode 12&13)
What if: After being pulled to the future by Ezra, then back to Malachor, Ahsoka knew what will happen in the future, so she went incognito again until she feel Kanan’s death through the force, then she sent a message to Rex so that he and Kallus can go fetch Wolffe and Gregor and head to Lothal to help Hera & co. to do what they must do to finish the Lothal business (I think Ezra still has unfinished business with Palpatine)
Since Hera & co. has no means of communication to contact people outside of Lothal, Ahsoka might be a surprise ally through Force/Fate’s mysterious way of working.
A Force Sensitive Phasesixer 