So Carrie Fishers daughter Billie Lourd is reportedly being cast as a young Princess Leia in Star Wars VII. Theres been no official confirmation of this yet AFAIK; and always in motion is the future.
But suppose its true. That probably implies a flashback. (I say probably because it could always be a holo-recording or something.) So the question is: why do the makers of this film want to include a flashback, and in particular one focusing on Leia? I offer a hypothesis.
Of all the Star Wars characters who are a) extremely popular, and b) not still alive in this movie, which would audiences most like to see in a flashback? Surely the answer is: Darth Vader. A Star Wars geek like Abrams would presumably love to direct a scene with Vader; and the suits at Disney would doubtless love to see Vader using his money-attracting powers in their new film. Hence the attraction of a flashback in a series that has not heretofore been big on flashbacks.
So where does Leia come in? Well, in the original movie when we first see Vader confronting Leia, he says, You werent on any mercy mission this time, implying a previous interaction. (A 1981 Star Wars radio-play even dramatises that previous interaction.) Might Abrams flashback be to that purported mercy mission?
If so, its possible that Tarkin will be in it too, since Leias words I should have expected to find you holding Vaders leash; I recognized your foul stench when I was brought onboard suggest both that shed met Tarkin before and that hed been in Vaders company when she did.
Why, diegetically, might there be a flashback in Ep. VII? Perhaps as part of some Jedi meditation trance on Leias part. (And if they want to have a meditation flashback for Luke too, well, Abrams can always just clean up and enhance the deleted Tatooine scenes from Ep. IV. Maybe Koo Stark will finally have her Star Wars moment on the big screen!)