Anyone noticed how in E16 there's a guy in a random pokecenter I think, who talks about a certain "Savage", a trainer who turned mad after several losses to Shade. He says Savage eventually beat Shade and is "likely further down the Reborn league now", though since we never encountered such a guy and we know the remaining gym leaders, could it mean that Savage is one of the Elite 4 now? Likely a ghost/dark user.
That would put the E4 as Heather, Bennet, Savage and El, in some order(El probably the strongest after the champion). I don't think Anna is E4.
As for the champion, either the final Lin fight will be after the E4, in Pokemon Black/White-style, or El might've taken over as the champion by then.