What do they do with the mining pools once they take over?
First, Turn off the miners. This is a very temporary attack and just means the BTC network is slow for a while and takes time to recover. A big deal, yes, renders BTC relatively unusable and tanks the value for a while. But despite all of that, the BTC network will say "never again" and learn the lesson of requiring geographically diverse pools. We might have to experience this before we fix it, but it won't kill BTC, the true ownership of keys and decentralization, which still exists despite the network being slow, will be resilient.
Second, Attack the network. the BTC network follows specific consensus rules, you can't go against those even if you control the miners. the other option is to re-write history, to do some transactions, spend some money, and then go back and re-write the Blockchain with "bad" data. This would undoubtedly suck, it would be very bad public relations for all crypto-currencies and laymen would not trust Crypto for another 10 years, they'd declare it dead over and over again until people finally admit it isn't dead.
First, Turn off the miners. This is a very temporary attack and just means the BTC network is slow for a while and takes time to recover. A big deal, yes, renders BTC relatively unusable and tanks the value for a while. But despite all of that, the BTC network will say "never again" and learn the lesson of requiring geographically diverse pools. We might have to experience this before we fix it, but it won't kill BTC, the true ownership of keys and decentralization, which still exists despite the network being slow, will be resilient.
Second, Attack the network. the BTC network follows specific consensus rules, you can't go against those even if you control the miners. the other option is to re-write history, to do some transactions, spend some money, and then go back and re-write the Blockchain with "bad" data. This would undoubtedly suck, it would be very bad public relations for all crypto-currencies and laymen would not trust Crypto for another 10 years, they'd declare it dead over and over again until people finally admit it isn't dead.
This is out of code, its unenforceable and unnecessary. The network will self adjust regardless of how much hashrate remains, always. Doesn't matter where the Geo-location of nodes it, the code doesn't care and shouldn't care because this could be faked or hidden anyway.
So what if you shut off the "4 main pools", again the network would adapt, assuming that a good portion of that hash rate doesn't migrate to the remaining pools which is highly probable.
Go back and rewrite the blockchain is not possible, you would cause a hard fork. And Ethereum already did the unthinkable anyway, they earned their stigma after that incident. Bitcoin never will.
To successfully pull a 51% attack you will probably need to spend far more money than any possible gains of doing so, especially in the largest blockchain with the highest hashrate on Earth.
Some "whales" have already tried, it didn't end too well to them.
