The most plausible explanation for Sherlock's fall (feat. Busted)

Everyone watched Sherlock on New Year's Day, right? Of course you did, you've had two years to catch up with the last series. It was a brilliant episode, but alas! we were not told how Sherlock managed to survive a deadly plummet from a really tall building, his supposed mangled corpse crunching onto the pavement below, all witnessed by a traumatised John.

I've thought it through and there really is only one explanation, exclusively revealed right here on Alma Grove.