An alternative is for C to D to equal .618 of A to B or about 29 points which is exactly what is in place. 83-54= 29 (A to B is around 47 points). Given price behavior, I think the market is taking this to be the case.
In either case, it could take prices up to the 2088 area and, in the course of doing so, form a beautiful which could give us a nice ride to new lows or a retest of recent lows.
The only thing that might ruin this pretty picture is failure at around 2074 as various calculations suggest this area will be tough to navigate.
In any event, I expect a ride up followed by a drive down.