While she has yet to appear in a live action movie, Ahsoka is a fan favorite character from the Clone Wars and Star Wars Rebels TV Series, and would be a worthy inclusion into the game as a supporting character.
Seeing as Cal was a padawan at the time of Order 66, the same as Ahsoka, it is possible that they bumped into each other at the Jedi Temple, and may have even been friends.
As shown in Star Wars Rebels, she also managed to survive Order 66 and went into hiding in the Outer Rim before joining the Rebellion years later after being recruited by none other that Bail Organa.
Seeing as she would be one of the few remaining Jedi working with the rebellion, it would make sense that she be paired with Cal at some point for an important assignment requiring multiple force users, possibly to face of against a group of inquisitors.
As previously mentioned, it is likely that Darth Vader, Ahsoka’s former master, will also make an appearance in the game as an antagonist, and as shown in Star Wars Rebels, Ahsoka also had a vested interest in confronting her former Master for betraying the Jedi order.
While I would not expect her to come face-to-face with Vader herself, as she does not first fight with Vader until the events of Star Wars Rebels, but she and Cal could work together to collect intel and track Vader down so that he can face the Sith Lord later in the game.
Regardless of how she is included, Ahsoka is a popular and interesting character from the TV shows, and it would benefit the game to include one of the few remaining Jedi in it.