Well, what I will watch for is a consolidation at the line and then a break below for a short. I am not predicting this, this is what I would like to see to set up a possible short scenario.
How one trader may make a play 'working' a trendline:
The thick red downtrend line on the attached chart is a good resistance area for a consolidation to build (energy to build) and then a move higher.
As well, the horizontal line at 13500 is a significant resistance area because of all the past heavy support/resistance. A trader could 'work' this area for trading decisions like:
* Go long if broken
* Go short at the resistance
* Take profits if long
* Take partial profits if long
* Move stop just underneath this area if 13500 is broken to upside