TLDR: Losing volume from Amazon isn't so bad.
As I worked support in a UPS hub in Jacksonville, FL, I can confirm that actually, losing some volume from Amazon will help. The facility I worked at was at volume capacity per hour over five years ago. Updating the belt system in the building is problematic due to space available and time lost during the shutdown. Year over year the volume has only grown as more people order more online. The capacity in that hub remains the same which means they have to run more sorts/shifts and the operations start to collide together and so on. A little less volume could be seen as a good thing. As long as revenue holds.