Once there are hardforks, people will be able to 'vote with their wallets', and a consensus will be apparent through exchance rates. Ethereum on the other hand

Once there are hardforks, people will be able to 'vote with their wallets', and a consensus will be apparent through exchance rates. Ethereum on the other hand wants to introduce the rather nebulous concept of 'proof of stake', under which something like you say might be feasable.