The price of AMD video cards will drop when either one of these two things happen:
The "optimistic" scenario: Someone develops an ASIC for cryptocoins using the script algorithm (like Litecoin, Dogecoin, and all of the other annoying Litecoin clones out there). Difficulty skyrockets, and it no longer becomes profitable to mine them with an AMD video card. This scenario has already played out for Bitcoin.
The "pessimistic" scenario: A bunch of large countries outlaw the exchange of Bitcoin into government backed currency due to new money laundering and drug trafficking laws. The value of Bitcoin plummets, taking Litecoin and all of the other cryptocurrencies with it. Mining coins is no longer profitable, so most people stop doing it. This scenario is already playing out in places like China and Thailand.
In both scenarios, you'll see a ton of overworked AMD video cards being dumped on eBay. I wouldn't buy them, as many of them will have been running overclocked 24/7 for months and will likely experience fan problems in the near future.
GPU Mining has now been going on for years. If you look at the Bitcoin Mining thread here dated 05/24/11 there were posts withing a day saying it already wasn't profitable. Almost 3 years later, people are still making money. The "ton of overworked AMD video cards being dumped on eBay" scenario still hasn't happened. Who knows when, or if it ever will?
Nobody even has to outlaw anything. There have been several times when the value of one bitcoin has fallen by more than 50%. There have also been several times when mining difficulty has doubled over a short period. If certain combinations of bitcoin price and mining difficult becomes the norm the mining will stop.
For example, ASICs have made GPU mining much harder but the move from Bitcoin to Litecoin also made GPU mining for Litecoin more viable. If a Litecoin ASIC is made, that makes Litecoin less attractive. Or cryptocoins could take another one of their speculative price downswings because the prices of these things aren't really rooted in any measureable way so they can fluctuate wildly in both directions.
Low enough prices prices with high enough difficultly and the miners will stop buying new hardware. If this situation persists for a few months the miners will strip their rigs and sell the components rather than lose the money.
Again, been waiting for this prediction for years now.
I've seen a couple of sites already taking orders for (non-reference) 290s at sub $500 prices. Most of them are shipping them out starting next month. I know that's not really returning the prices to normal, but it's a start. It's definitely going to be a while before we see Radeon prices go below MSRP.
My guess is give it another quarter or so. Mining will most certainly be profitable even then. However, by that time ASICs will be closer to release, supply will increase, and demand will start to level out.
NCIX has the Asus reference 290 listed at $439.99 Back ordered with an ETA of 3-5 days.
Superbiz is showing the Powercolor reference 290X in stock @ $589.99 + $4.99 shipping.
Suprebiz also has the XFX reference 290X in stock @ $589.99 + $10.00 shipping
B&H often shows stocks near retail in stock.
Just check
http://pcpartpicker.com/ you can usually find some 290/290X in stock or coming soon near retail prices. I would call these places first before ordering to verify availability.
As far as the likelihood that it will ever die goes, I'm not so sure it ever will. There has been a push since the 60's for there to be a one world currency. Financial institutions in the name of nationalism has blocked it from happening. Depending on who is exactly behind this and the muscle they have to push it on, this could end up sticking. Lot's of national currencies around the world are basically worthless on the free market. People are often forced to do business in USD. I know the company I work for still purchases imported goods using USD. A one world currency would eliminate this and the associated fees to the bureaucracy that makes a living off of exchanging currencies.
As far as people not thinking this will effect the overall GPU market, including nVidia, think again. This drives up overall demand. People who normally wouldn't buy video cards at all, or might only buy one or two, are buying them in quantities larger than ever. As some have noted, this will make nVidia cards, which are more readily available, increase in demand as well. If it increases demand enough, prices will go up. I believe that if this hadn't happened and we continued to see AMD cards at MSRP we very well could have seen nVidia prices drop some by now. The 290 @ $400 very well could have put more pressure as time went on , on the 780, for example, and forced it's price down. Or the custom 290X's at $550-$600 would have pressured the 780 ti. Surely nVidia cards wouldn't be as good a value as they are now without AMD's prices being inflated.