I think theres a issue with your predictions: You assume that the miners act rational. I think its more like: "what, I can produce money? sounds good! lets do that!" If people would act rational, the grow of the hashrate would have stopped long ago. So I think that the hashrate will keep growing exponentially and therefore pushing the price of bitcoins up.
Another thing to consider is the endless pool of new people getting into the game. I wish I knew what percentage of products the miner manufactures sell are repeat customers. Most business rely on something like 80% repeat business. If this is the case for mining hardware companies they will quickly go out of business.(quickly like in 2 to 5 years) But I think the reality is more like 20% repeat and 80% new with a huge lineup. The lineup of people who cant do math and think this is get rich quick is huge for now. But bitcoin is still a tiny market and something like 1% of users holding 80% of BTC. So in the long run it may be good. This is just the growing pains of a new market.