Once again, the "prophets of apocalypse" are forgetting the most precious natural resource that exists: human creativity. As the bitcoin market increases and attracts bigger companies, the competition for the fastest mining machines will eventually lead to more investment on improving the power efficiency of current processors. And this will not only benefit bitcoin mining, but also any other heavy processing tasks. It can even improve the energy consumption of cell phones, for example, and that would lead to more durable batteries, which is another pollution source today. And, if the mining costs begin to reach the value of their rewards, the interest in mining will simply diminish, reducing the amount of complexity and again making it profitable. That's simply supply and demand, and it was not invented with bitcoin. It's a concept motivated by basic human instincts, and has been present in our lives since pre-history.

I think it's better adopting integers and cents instead of fractions, as suggested by the user ronwan in another topic (quoted below). Personally, I don't care if those integers are called Naks, Satoshis, microbitcoins, mikes, coins, republic credits, bananas, or anything else. We need a notation more on pair with common people's understanding if bitcoins are to be adopted worldwide. There's also the possibility of hyperinflation if regular people don't fully understand the real value of their money, as occurred here in Brazil during the 80's and early 90's.

We had a sequence of bad economical plans every 2-4 years, each of then cutting 3 zeros from our currency, and even changing it's name from Cruzeiro to Cruzado, then to Cruzado Novo, back to Cruzeiro, then to Cruzeiro Real. It was only in 93, when our then Minister of Finance Fernando Henrique Cardoso (a sociologist! - after that elected President for 2 mandates) decided to hire a group of economists to create a definitive economic stabilization plan, that our inflation was finally tamed. They created an indexer, called URV, initially paired to the dollar, by which the prices of goods were adjusted on a daily basis. That way, our former currency, Cruzeiro Real, continued to be depreciated during the period of a year, while the new currency got stronger in people's minds. After this year passed, the government printed the new paper currency, called Real, which replaced the URV and got the "respect" of the population, ending almost 15 years of hyperinflation. During the first years it even surpassed the dollar in value. Today, 20 years later, after all sorts of economic turbulences, one of them caused by the fear that a socialist party (PT) would win the 2002 presidential election and ruin our economy (in fact, they won that election and the next 2 and actually almost ruined it!), we may not have the strongest currency in the world, but inflation is still under control.

In short, the stability of a currency is much more influenced by people's notion of it's value than most other factors. And how are we expecting to give then this notion if the majority of the world's population doesn't even understand the concept of fractions? Can we imagine making them understand SI prefixes or negative powers of 10? If we want bitcoin to be adopted worldwide, we can't have a currency which value is only understood by programmers, engineers and mathematicians!