When I say ideal I mean:

• People cannot born them from blown air and some day they will not be able to earn from coinbase's rewards.
• Over time, it will still have value.
• It cannot be spoiled by human.
• It is decentralized, no one controls it.
• You can send/receive the currency really quickly.

These are some basics requirements for the ideal currency. But I have a question. There are public and private keys out there. You can take anyone's public key and send him/her bitcoins. In the future, like 2100, you understand that technology is advancing. Those years I believe that brute forcing a private key will not be something impossible. Do you think that bitcoin will be spoiled by human in the future?

Should bitcoin use SHA512? Or something even stronger?