Hasn't anybody read Kurzweil's book on Law of Accelerating returns - the rate of technological advancment is exponentially increasing. The CPU processing power used to double every 4 years, then 2, now it's less than a year and so on.
Same is happening with the GPUs as well as other technologies - now I am not saying that 6 years from now the GPUs will be 560x faster - but the rate of progress six years from now will be MUCH greater than the last 6 years (due to law of accelerating returns).
Us human beings tend to think in a linear fashion - predicting the future based on how long things took to develop in the past - and technology doesn't follow those trends.