No. There wouldn't be any unsold stockpiles.
Making more cards = miners getting more cards.
As long as anyone can make >$200/month with any Vega and >$100/month with any RX570/580 (of
profit considering $0.18/kW.h), miners will get all the cards directly from the factories.
They're money-makers with full return of investment after 4 months that still retain a good chunk of their value if sold in the second-hand market.
The moment AMD released that blockchain driver back in August 2017, they pretty much killed their presence in gaming desktops.
Maybe they got afraid of not selling enough Vega cards and/or they weren't counting on the explosion of alt-coins designed to be ASIC-proof, but that was probably their 2017 decision with the worst outcome.
Curious thing is had they made the driver exclusively for Radeon Pro and FE, AMD might have been swimming in money right now, as even the FE would still be very profitable.
For example, the
Radeon Pro WX7100 is selling for less than most RX580 cards (that are actually available), it probably mines just as well and AMD gets a much bigger share from those than the gaming cards. Same thing with the
WX5100 and the
Vega FE (
which AMD now promotes as a card for "blockchain pioneers".. lol yeah right too late now, guys).