As a point of comparison, the total number of 767s ever delivered (all models) is 1,097 -- including 1 delivery to FedEx earlier this year.
And the largest ever 767 order was placed by FedEx two years ago, for 50 aircraft.
Not counting conversions, there are only 123 767-300Fs deliveries in total.
An Amazon order for 100 (or 400!) would be monumental for the 767 program.