Well..The previous champion of Reborn was Ame and she died because of Lin, so that leaves us without a champion at the moment. We are the ones who try to take up on the title officially. In my opinion, I think Lin will become the champion because she's the big bad out there. The biggest twist of them all would be Fern as the champion (unexpected but oh so expected).
As for the elite 4 members, I'd love it to be some of the people that are presented on your list but I think that Anna is a substitute leader (We can never be sure though.).
But if Laura was in the Elite 8 and she needed to be out of her position, for Bennett to replace her, that means: 1). Laura reclaims her place and Bennett is out.
2). Laura never reclaims her place in the Elite 4, so she's not one of them .
3). Someone else retires, so either Laura or Bennett are in the Elite 4.