There will be plenty of time for pundits, analysts and investors to diagnose and debate why AT&T (T) couldn't successfully drive value from a media business (then known as Time Warner) it spent a whopping $85 billion on to gobble up just three years ago. But most outsiders would agree on one thing: AT&T sent a good bit of shareholder value up in smoke by trying to be the king of content and distribution. Driving value from the now WarnerMedia portfolio will soon fall to a new partner, however.