Apple just hit a $5 trillion market cap for the first time, but CEO Tim Cook still has plenty of concerns to address on his final earnings call at the helm. Brendan McDermid | Reuters Tim Cook's final earnings call as Apple CEO takes place the same week the iPhone maker touched a $5 trillion market cap and surpassed Nvidia as the world's most valuable company. But there's no time to celebrate. Even with ... [5650 chars]