$FedEx(FDX.US), the U.S. shipping giant seen as an economic bellwether, bombed at the start of the new fiscal year with negative sales growth and profits plunging more than expected, reflecting weak demand in the parcel delivery industry, especially in FedEx's priority delivery services. To make matters worse, against the backdrop of persistently weaker-than-expected freight demand, FedEx also lowered its revenue and profit guidance for the current fiscal year, leaving investors worried about the future. What's next?