I wonder how things would have gone had Kalanick's family hadn't suffered that horrible tragedy a few weeks ago. That is, whether he would have had the energy/stubbornness to stay as CEO if he wasn't dealing with personal challenges at the same time as professional ones.
I'm sure that was a big factor. Turning a firm's culture around in this case would mean reinventing himself at the same time at the firm, and while that's doable it's a full-time thing. The loss of his mother and serious injuries sustained by his father in the same accident were a cruel twist of fate that would derail many people under the best of circumstances, never mind these more difficult ones.