I see a couple problems in the immediate future. Now hear me out before you try and answer these in your head.
Maximum volume will be 21 million BTC. However this will not satisfy a global market.
The United States alone has trillions of USD. Now I understand that BTC can be broken down, but read on.
Significant difficulty increases and current value of BTC are leading many to cease mining within the next 60 days.
A growth stunt at 80K users is a real issue! We need 80 million, not 80 thousand!
Addressing Problem 1: (Insufficient Volume for a Worldwide Market)
Ok.. your thinking this isn't really an issue since someone can just sell a pair of shoes for 0.000050 BTC, yeah yeah... but I'm telling you that will never settle with humans.. ever. People don't want to hear that their products are only worth 0.00005 BTC. But here's the solution. Change the client software to uBTC (micro-BTC). People will be inclined to sell a pair of shoes for 50 uBTC. Even though this is the same number, this gives the BTC World Market 21 trillion uBTC - fit for a global economy, and a more psychologically friendly usage of numbers.
Addressing Problem 2: (Growth Stunted at 80K-120K Miners)
People are about to walk away, sell their rigs.. tell their friends the easy money is over. Your thinking they're whiners, too bad they missed the goldrush and they can just go crawl under a rock. The truth is, we need 80 million, not 80 thousand. So this is a problem. Now, if we switched to uBTC in the mining clients, they would see they are ALL still early pioneers, not earning .05 BTC per day, but earning 50,000 uBTC per day. Obviously if the world caught wind of this 50,000 per day opportunity, and the growth exploded more (eventually to 80 million miners), then people would be earning more like 50 uBTC per day (1000 times less). Now we are at a more realistic mining rate at the global level. 80 million users = a real economy.
What do you all think about uBTC? Would it help today, tomorrow, eventually?