I have a friend who slipped on some ice and broke his femur! This was 5 years ago, he was an avid cyclist but he still has issues today that affect how much he can ride.

Unexpectedly slipping on ice is no joke! That being said, if I can't xc ski I go for long runs all the time with microspikes and trekking poles. So the gear to be safe (with common sense and knowing ones limits) does exist.

I don't want to overdramatize the fall as I feel better now, but I can see how it could be worse for older / taller people in a slightly less fortunate fall: one might fall in front of a car, bicycle, one could fall and break a leg or arms, roll down a little hill right into a forest, lose a tooth or two, punch or pull someone else as they fall etc...

Brain concussion, spinal injury etc., depends on what you hit on your way down and how hard it is; fences, kerbs etc. may be very unforgiving.

I once slipped on ice on a pavement with enough energy that I almost ended up in the street next to it where cars were going their normal 40-50 kph. (The street had quite a slope, Prague has a lot of hilly neighbourhoods.) I caught myself on a street lamp before drifting out to the danger zone, though.