Looks like suspicious packages are still showing up in cargo planes. If a cargo plane had an in-flight explosion, what would have been the response? Would all cargo plane traffic come to a sudden halt? As it is, there have been disruptions and delays. So far as I can tell, minor problems.
How much of the world's cargo is transported by plane? How big a part of the economy is it? What would the economic ramifications be? Cargo is shipped by air when time is a factor. If a factory needs a critical piece of machinery, they don't want to wait weeks or months for it come in by ship. They'd have to, if cargo air was shut down. What would the ripples be in the larger economy? How about critical medical supplies? Emergency relief supplies?
The world would get much bigger again. With quick air travel, no one gets too upset if some critical item is only available from a handful of places or even a single source. Planes can haul it in a matter of hours. If that quick delivery was no longer guaranteed, would more diverse sources be developed? Is there time for that to happen? Maybe the disruptions could be one more destabilizing factor in an already wobbly global economy.
Perhaps the real target isn't who the packages are addressed to. That may be a red herring. The real target might be the cargo planes themselves.
In war, it makes sense to take out the supply lines. If the enemy is the western nations, then grounding cargo planes would make tactical sense.
Let's see if anything happens to shipping. That would be another logical target in asymmetrical warfare.