Chronic shortage of RX-480-580 video cards

In the last couple of weeks I have noticed a shortage of RX-480/580 video cards from all of the major online retailers.
I know the 480 was replaced by the 580 but I would have expected to find at least some of them online.
Any one know why the 480s and 580s are in such short supply?
 
MERGED QUESTION
Question from gdmaclew : "Chronic shortage of RX-480/580"



 


The 580 and 480 are extremely popular because they give 1060 performance for a bit cheaper.
 
This is ridiculous! It's now 2 weeks since I've seen any RX-570 or RX-580 on any of the major computer parts sites. That goes for Canadian sites as well. They may be popular but it may ultimately hurt AMD because in a pinch people may spring for a 1060 instead. I'm not one of them.