Sunny, if price falls and if miners stops mining because price falls and the supply of coins increases because of falling difficulty (yes a lot of if's and perhaps it will not unfold like this but IF it does happen this way [please humor me]): then do you think that it is possible that new miners will step in to mine these easy/cheap coins - hoping that difficulty and then price will go up later on therefor considering it a bargain thus pressing up the difficulty yet again creating aa self-fullfillinng prophecy?
There may very well be speculations on miners' side I don't know, but the point is over long term the effect of Moore's Law plus algorithmic/hardware improvements would overwhelm any demand changes anyways. Demand typically fluctuates within 2 orders of magnitude, while Moore's Law + algorithmic/hardware advancement would reach over 5 orders of magnitude or more over long term. For example in bitcoin network, it went through about 4 orders of magnitude within the first five years.