Yes, this is very worrisome. There was a post on the company web site a few months back from Fred Smith, addressing this issue. It was a very well written synopsis of the situation. The bottom line was, if this passes FedEx will be bankrupted in short order. Not due to the unionizing but due to the disjointed and localized method of the unionizing. He spelled out exactly how this would happen.
I know what all the old heads will say; "we received the same letter when we were trying to unionize". However, this would occur on such a large and disjointed scale, Fred Smith is probably right. But the good news is; this would give the government one more industry to take over and run.