If you plot price rises against difficulty you will see there is a price rise in line with difficulty rises, so even if you can only mine a lower amount of BTC, then the price you get for them is higher also.
Are you sure about that?
Maybe before Mai 2011 but now its more than questionable. Lets look at June to July difficulty and BTC price.
We started out somewhere around 0.6 mill and now we are at 1,69 mil - this is more than 280% rise in difficulty.
BTC was trading around 10 in the beginning of June and now we are at 13-14 USD. I see 30% rise (not bad at all). Forget the jump to 30, this had nothing to do with difficulty.
If you look at the July data, picture is quite the opposite to your prediction. Difficulty jumped from 1.2 mil to 1,69 an this is almost 40% jump. At the same time, BTC has fallen from 17 to 13.5. Do be honest, this a bit strange.
BTC needs more businesses to accept the coin and not more miners to flood the market. In long term, I am bullish and I believe that more businesses will starting to accept the coin.
This need some serious PR work and selling.