That is an awful story -- that poor little dog! And the people too, that would be devastating!
I used to live in a 500 unit apt complex that was frequented by coyotes, and they were fearless of people. My old dog Jake was terrified of them, somehow he knew when they were nearby. But he was 2" under the breed standard and had undergone surgery for hip dysplasia.
My new Jake, in contrast, is 4" over standard, and he ain't afraid of nuthin -- just ask him.

I do wish he was a little more fearful, I don't think he'd stand a chance against an adult coyote.

Luckily we don't see many of them, even though I now live in a very rural setting.
A couple of notes... I've seen proof that coyotes can scale a 6' fence without difficulty, but there's a product that makes a 6' fence impenatrable by them, called Coyote Rollers, a little pricey last I checked, but very effective.
And about hawks, several sources say that a hawk won't hunt things it can't leave the ground with, which limits prey animals to those less than twice the weight of the hawk. Most hawks weigh well less than 3kg (6.6 lbs) and a nice fluffy Sheltie looks heavier than it is, so most adult Shelties are pretty safe.
We have a lot of hawks and condors around here, the hawks were interested while my dogs were puppies, but not at all now. From my observations only a desparate hawk would try to take prey that outweighs itself, they stick with smaller things like mice, squirrels, swallows, etc. (Condors are always interested in anything that might be dead someday, but I'm told they never hunt live prey.)
Oh, and about never turning your back to a coyote, I strongly agree. Coyotes are canines, anything that runs away signals game on, and you'll never out-run one in 1,000,000 years. On your feet you're potentially threatening. On your knees, you look weak and injured. On your back, you're a meal.