The issue to me is that it does not seem to fit with the existing storyline whatsoever.
At present, the missing (insane?) emperor has returned due to Revan messing up. This emperor just essentially wiped out all life on an imperial world and that's where the story is now. The expansion doesn't sound like it connects at all, although they still have 3 months to connect it I guess.
Aside from that it says nothing about the game itself. We know that there'll be nine chapters come October, and they'll continually add new ones, new companion (and you apparently get to kick out an existing one), level cap up to 65, and subscribers to get lots of rewards between now and then, along with the new story lines, and apparently being able to affect different outcomes.