Mayor players (exchanges, bitpay) could decide to just ignore the dominated branch of the blockchain, by requiring that block n has hash h. This would lead to a fork similar to etherium vs etherium classic.
Alternatively they could start not to accept the spoiled coins. If account a double spends x, they track where the coin goes, let’s say b accepts y:=x-? coin then a still has x-y spoiled coins and b now has y spoiled coins. Now you just don’t accept transactions from accounts that have spoiled coins. Would work with bitcoin.
Also the government can come up with similar regulations to crack down on bitcoin.
> If account a double spends x, they track where the coin goes, let’s say b accepts y:=x-? coin then a still has x-y spoiled coins and b now has y spoiled coins. Now you just don’t accept transactions from accounts that have spoiled coins.
That would be a perfect way to lock another user's account out of exchanges. Care to give me your address? I'd like to send you some spoiled bitcoins I have lying around... ;)
As for the government, you can be sure they are already tracking all of the transactions. Bitcoin is far from anonymous - cash is a better alternative if you need anonimity, and even that can be traced easily nowadays.
Well, if you attack me like that I can always pass on the spoiled coins to a newly created account. Once I got rid of the spoiled coins my account would be clean again.
In a regalutory framework there could also be filter addresses that launder your coins for a high price (99%).
But how fast can you do that? Wouldn't the double spender immediately tumble them by exchanging them for other coins across a bunch of different exchanges making a fork to fix it nigh impossible.
Alternatively they could start not to accept the spoiled coins. If account a double spends x, they track where the coin goes, let’s say b accepts y:=x-? coin then a still has x-y spoiled coins and b now has y spoiled coins. Now you just don’t accept transactions from accounts that have spoiled coins. Would work with bitcoin. Also the government can come up with similar regulations to crack down on bitcoin.