At a recent interview at Goldman-Sachs Naval Ravikant had explained bitcoin as a fly trapped in amber, with new layers of it being added by the mining process. Among other things this prevents adversaries from messing up the blockchain, as that would require a consolidation between 50+% of miners. No one has the computational power to do that, so it is safe for now.
So here is a question to all of you blockchain experts: what happens when the last block of bitcoin is mined? All the miners are going to stop applying new layers of amber, and only transactions will remain. At this point, is it going to be possible for a powerful adversary with a supercomputer or a large botnet to drive the blockchain off the rails? Will new transactions after this period no longer be safe? Or is there some sort of mechanism that will prevent that from happening?
