What creates price bubbles is not the deflationary nature of Bitcoin (which we aren't even observing yet); it's the fact that the supply is perfectly inelastic. With most commodities, when a speculative price bubble begins to form, profit motive drives production to increase, and the increasing supply counteracts the growth in price. But Bitcoin is different: no matter what the price does, the production is always at an approximately constant rate. Thus, there is no moderating effect on an increasing price, and we get speculative price bubbles. I personally believe we will continue seeing this "plateau-ramp-crash" cycle throughout Bitcoin's adoption. However, I do think it will moderate in amplitude as the market grows.