I'm going to quote myself, this is from an email I wrote yesterday to somebody else concerned about chip/mining centralization:
Quote
I think it will go through waves of centralization/decentralization. I can imagine bitcoin-mining electric hot water heaters installed in homes all across the world, installed by thousands of private companies that split the profits with homeowners. And thousands of die-hard do-it-youself-ers who buy the hardware and cut out the middleman.
In the very long run, mining will be dominated by your cost of electricity and your ability to put the excess heat generated to good use.
I don't think it will matter what algorithm is used or even if the algorithm was changed every six months; if a general-purpose CPU was the only thing you could use for mining, you might see general-purpose CPUs designed to operate at thousands of degrees celsius being designed so that aluminum smelting plants can also mine bitcoins with all that electricity they use turning bauxite into aluminum.
In the short run... I think there is zero chance that "we" will decide to change the hashing algorithm.