Sorry, but what culture do you believe Bartz destroyed? I was at Yahoo before Bartz, and left only about a month before she was fired. I don't believe that Bartz destroyed anything. Yahoo has never had a great culture. They've always had an identity crisis. You can go read PG's older essays and see that.
Bartz was fired because she couldn't work a miracle. Yahoo needs some truly amazing changes in order to avoid Sun's fate, and I'm not sure anyone out there can/will deliver what's needed quickly enough. You mentioned Apple as a turnaround example. Exactly where do you think Yahoo is going to get a Steve Jobs?