I couldn't agree more on the current state of Chung, Aus. I wasn't quite as optimistic as some in regards to his return, but he certainly does add something with his quickness and ability to thump. His coverage skills basically suck, or at the very best are mediocre, but there is certainly the possibility that he can make another step forward there too.
As far as the DB's go, I think that we're going to see something a lot better this year. I'm high on the versatility angle, which will allow Belichick to have the option of switching things up if/when the time comes. I think that will go a long way.
Although Moore may not be quite what some make him out to be, I also believe that he is the kind of guy who offers a lot as far as finding the ball and attempting to make a play on it. It also helps that he can switch back and forth between secondary positions if needed. Should McCourty falter again at CB, we'll be seeing him in other areas, so they should be able to play more to his strengths in that regard.
Arrington did well in the slot, so I expect him to be there, barring injuries of course.
If Gregory or Wilson are not cutting it as one of the quicker, roaming safeties, then we'll see a change there too; there seem to be a lot more options this year, as long as the majority can stay healthy of course.
Allen and even possibly Dennard may end up showing us something too.
If we can luck out in the injury dept, it could be a much more talented and deeper unit altogether.