Quote from: blacksmithtm on April 05, 2013, 03:57:49 AM

But when there are no longer coins being introduced, some miners will leave? They would have pushed the difficulty way up, and when they switch of their machines, well then what

You're talking about over a century from now. At current rates, there is still going to be a block reward until ~2140 if I'm remembering correctly. That, and there's always going to be transaction fees included in the blocks.

Of course people are going to switch off machines as they become not profitable, however people are always adding new machines that are profitable and more efficient. So, I don't see difficulty ever really decreasing in any meaningful amount.

The 10 minute time is just arbitrary, the network changes the difficulty of the problems to get to that average time.