Imagine the following scenario:
- AMD significantly ups its production of, say, R9 290. (Exchanging wafer capacity for a lower product to this one, because TSMC is pretty much always close to full capacity.)
- Silicon order to cards ready is 3 to 4 months.
- Meanwhile the coin craze dies.
This also assumes that the GPUs are the limiting component. Not every card shortage has been attributed to that, and a sudden spike in large memory video cards and those high-speed power controllers might hit someone else's supply constraint.
It may not require that the mining craze die down, rather if scrypt ASICs can become popular enough to make GPUs less favorable in terms of rig cost or power consumption, or in the worst case become dominant enough to force the mining difficulty too high for multi-kilowatt GPU rigs to pay for their electricity bill (possibly already the case in countries with higher power costs).
It seems like this starts for Litecoin around mid-2014, although the ramp may take some time.
Even without that impact, the GPU-amenable coins with some fixed total number of coins or slowly expanding monetary base still become more difficult over time, and return on investment is already much lower than those who got in when it was easy.
Miners with GPU rigs are already discussing which $coin they can hop to next, gambling that they can convert the seigniorage of the early part of the difficulty curve to a somewhat acceptable conversion rate to slightly less recent $coins all the way to Bitcoin, or directly.
It's a pyramid of illiquidity that really doesn't show a long future for them, and for all we know the next struggling generation of cryptocurrencies will be one of those being specifically tailored to gut both ASICs and GPUs.
I do fear that AMD may be facing a glut of used Tahiti and Hawaii cards late this year or the next that could depress the perf/$ ratio and hurt any new products coming out, unless AMD's next round of products is a much greater jump over its forebears than has been the case for quite some time.
The assumption that you are making is that AMD either didn't know about, understand, or care about mining and therefore didn't set initial or subsequent runs high enough. I continue to believe there is a fly in the ointment somewhere in the production and we just don't know yet. Until the 2014 WSA is released and we get more info on what is made and where...
I'm not sure when scrypt-based coins like Litecoin or Dogecoin were able to reach a level of acceptance, and even if AMD made a bet on a cryptocurrency, it could have bet on any of the many others that haven't.
The standard bearer Bitcoin is completely out of reach for AMD cards, so some of their data would have been indicating that it was too late anyway.