I will say that if we do see flashbacks in the new film, it would likely be dragging the franchise into a more modern style of filmmaking.
Remember the LOTR trilogy? That had quite a few flashbacks. For instance, when Elrond says that he watched in horror, three thousand years ago, as Isildur took the One Ring for his own, we don't just hear him tell it, we see it happen before our eyes even as he's speaking. We leap backward three thousand years and forward again, seamlessly, all in the matter of a few seconds.
The emphasis in modern blockbuster films is on showing the audience what happened in the past or "off-screen," as opposed to just telling them. The problem with this is that it's a very arty technique. As such, it conflicts with the previous SW "house style" of fly-on-the-wall documentary-style filmmaking, whose whole goal is to make you forget there's a director behind the camera.