Mt. Gox is an exchange, if you want to sell your BTC for USD there must be a willing buyer available. Mt. Gox only role is to match buyers and sellers.

It would be helpful if the mining algorithm could be modified to minimize the impact of processor type.  Supposedly litecoin was designed in address this.  It might not be feasible for bitcoin to change that much at this point, but it's possible that Satoshi considered this early on and isn't concerned with the implications.  Only if we see the network hash rate really spike, and make the difficulty jump with it, will we know the impact on the network as a whole.  Smaller miners, like myself, might just bail if the block mining expectancy jumps by years.