It may be possible to survive such a fall through landing on your feet, but you'd have significant ankle injuries
I know someone who fell 20' or so and landed on her feet then dropped to her butt. No ankle injuries, but most of the metatarsals were broken and she had a small fracture in one of the lower vertebrae.
I think it's one thing to randomly survive such a fall with minimal injuries, but to plan to
deliberately
survive a fall is another matter.
But I'm sure Sherlock will have various and sundry facts to astound us with as to why he was assured of his survival, and survival in the best of terms, not just alive as a vegetable or a parapalegic or laid up for a year with every bone in his body broken.
If nothing else, it made for some immediately emotional fanart narratives.
I assume he landed on something that neither John nor the assassin could see because the view was blocked.
OMGWTF has Sela Ward done to herself? I didn't even recognize her on House!
I feel like in the tradition, it's fine for it to be an unsurvivable fall, because that's how Conan Doyle wrote "The Final Problem," with Holmes dying on the Reichenbach Falls for real, and then took it back.
Did Ward's character and Cameron die on House?
I have to say, I prefer the movie version of the Reichenbach Falls, because it's pure human protective instinctive emotion, a split-second decision (and that the surviving was reliant on a bit of five-fingered discounting of a random doohicky), as opposed to this silly trickery and manipulation that seems too complicated and dependent on too many variables. And cold and calculated. Until I see the mechanics, I can't believe the emotions Sherlock was showing in that final showdown. The whole thing stunk of meta manipulating to make certain things work out, and not character-driven decisions. (Yeah, yeah, I know there was Sherlock's earlier scene with Molly setting up some sort of subterfuge, but, that seems to rely too much on Sherlock being omniscient. I guess, in the end, I'm not as engaged by clever craftiness and chess-thinking that almost leaves no room for gut and heart. Although I'm sure everything I just said is fighting words for someone).
Did Ward's character and Cameron die on House?
Nope. Stacy married the other guy and lived happily ever after, and I think Cameron just left.
The whole thing stunk of meta manipulating to make certain things work out, and not character-driven decisions.
I kind of feel that way about the whole series.