> It really doesn't take much, even a few hundred people running low-power ASICs will do just fine.

That won't work - it will enable easy fraud since anyone with a moderate amount of computing power can fake the block chain.

You need a lot of computing power - but without large rewards people won't be willing to do it.

I don't expect any crypto currency to survive unchanged past the no-more-coins date. Instead I expect the date to be extended to forever.