Under the rule of John Donahoe, eBay (EBAY +0.99%) has undergone a massive transformation. Between all of its segments, the company expects that by 2015, it will enable more than $300 billion in global commerce, which represents an increase of more than 70% from 2012 levels. But like every great growth story, there are obstacles to overcome. In this video, Fool contributor Steve Heller weighs in on what will keep eBay from meeting its aggressive goal.