Lemme put that another way...
This company, which allegedly represents a clear and present danger to the duopoly, owns no aircraft and has no orders for new or used aircraft...but rather has short/medium term leases on airframes and selects CMI carriers to operate them on short/medium term contracts.
And some of those CMI carriers have major labor issues, making staffing and operating these airframes problematic.
Combine these Prime Air realities with widely the reported reliability issues of Amazon’s in-house last mile delivery and I believe the “threat” is exaggerated.