From the article/police account, both the pedestrian and the cyclists were heading in the same direction. If they didn't call out even a simple greeting to alert her, how would she even know that they were there or fast approaching to pass her?

On that same trail, and on that same day, I had multiple opportunities to call out my presence - both in passing walkers, skaters, people standing and talking with their leashed dogs blocking the path as well as those that were coming towards me from the opposite direction and were taking up most of the path...it's a safe and simple courtesy in sharing the trail, as I see it. I've always made a practice of calling out when I'm passing or to get someone's attention as I'm approaching and yes, I think it's rude and dangerous when others blow right by, as if they're entitled to every bit of space on the trail/road and too bad about anyone else.
No one should've been hurt here, and the loss of life is so senseless to me.