The finale reveals that Baylan Skoll is searching for a great power that is somehow connected to the Mortis gods, composed of the Father, the Daughter, and the Son.
They each represent manifestations of balance, the light side, and the dark side of the Force, respectively. At the end of their "Clone Wars" story arc, the Mortis gods die.
Now fans in a Reddit thread with more than 1,4000 upvotes are suggesting that Ahsoka will take the Daughter's place, alongside Anakin as the new Father and Baylan as the Son.
If true, then Ahsoka becoming the Daughter would confirm her deeper connection to the Force, which is how she would have been able to reach Rey in "Episode IX."