The question is will revenue overtake costs as it grows more quickly - no serious analyst would insinuate Uber will be gross margin unprofitable over the long-term. It would be awfully difficult to do so given they collect a percentage of every sale.
Uber has opened offices all over and has high fixed costs. It’s waiting on the small variable revenue from each trip to catch up with those costs, and the question is “will it?” That’s all.