Would prefer memory intensive rather than processor intensive proofs of work. ASICs make too exclusive and small the number for who possible mining is. 51% attack real worry for bitcoin.
51% attack can destroy bitcoin value completely. May not be profitable in bitcoin but possible do for reasons other. Imagine Chinese gov't considering people bypassing currency controls, or worse funding "terrorists" who want free speech. If is considered "Existential Threat", expect no hesitation on part of gov't to spend enough to destroy network, even when not profitable the destruction.
Also consider financial businesses eating whose lunch is bitcoin. What problem has toll troll making $Trillions on transaction fees spending a few $Billion to protect business from impending destruction?
Proof of work amenable to custom ASICs is worrying like finding half a worm in remaining apple.
2This is a very open ended question. If you focus it, you could probably get better answers. – Nick ODell – 2013-03-14T03:09:14.093
Actual decentralization. Making the 'mining' if there is any, be useful computation if possible. – placeybordeaux – 2013-03-14T03:30:54.483
@PeterMichealLacey-Bordeaux: The mining is useful computation, it secures the blockchain. – David Schwartz – 2013-03-18T04:01:15.463
But that is literally it. There is no reason it couldn't be folding proteins or something that the rest of humanity could do. It just needs to be hard to do and easy to check. – placeybordeaux – 2013-03-18T16:55:26.690
What about the infastructure of next gen crypto currency, what about implementing mining capabilities with renewable energy sources. Are crypto-currencies sustainable? How can crypto-currencies be made more sustainable? How much electricity around the world is being used at the moment to mine bitcoins? whats the carbon foot print? What will it be in the future? – user2103681 – 2013-03-17T20:53:10.663