Hmm, I wonder if or how easy it would be to upgrade the bitcoin network to use SHA3 in the future. Is SHA256 (aka SHA2) that vulnerable to "cracking"?
People say it could be done, but I think more importantly SHA256 will probably last unless there's a fundamentally new sort of compromise. It likely won't fail because of improved hardware over the next 20 years, unless we get a kind of improvement that we'd have no reason to expect.
The only thing that I can think of at this moment that would qualify as an "unexpected improvement" (well sort of unexpected) would be a quantum computer capable of making use of a surprisingly large number of qubits.
Now on to the subject of the thread. I personally don't think bitcoin mining is pointless. I like to think of bitcoin mining as sort of what a stock exchange's transaction processing systems do. They process the necessary transactions of the exchange and in return earn a fee for their work. Miners do very much the same thing. Thus the energy expended as a result of this process is not "wasted" or "pointless" because it is used to accomplished a desirable and absolutely necessary task.
If one argues that bitcoin mining is pointless, that is sort of like saying the energy used by cars is wasted or pointless because it doesn't cure world hunger. Kind of silly way of thinking.
To phrase it differently; No use of energy that results in a personally or socially desirable outcome should be considered wasteful.
Perhaps someone can refine my phrase a bit better. But anyways, I was quite surprised when I first saw this thread because I never quite expected that someone would question the usefulness of one of the KEY and ABSOLUTELY necessary components of the bitcoin system.