I always assumed that KotOR 3 would follow the premise of the other games. In KotOR 1:
Revan defeats Malak and saves the Republic or Revan becomes the Dark Lord of the Sith and resumes the destruction of the Republic.
Then, in KotOR 2:
The exile reseaves a quest from admiral Carth Onasi to find Revan or the holocron of Bastila says that Revan dissapeared, abandonig his apprentice and companions
Now, in KotOR 3, I think it should be the continuation of the "quest" to find Revan, possibly using the Exile again, maybe not. Maybe you have to race the Sith to find Revan, who could help save the galaxy, or bring untold destruction to the Republic. What do you think?