As you probably know, the Bitcoin network is scheduled to experience a hard fork on November 16 that will probably result in a permanent split of the Bitcoin network.
We have seen this before with Bitcoin Cash (BCH) and Bitcoin Gold (Although not yet available), but this hard fork will have an important difference with the previous two. The signitors of the New York Agreement (NYA) and the SegWit2x developers don't want to create a new altcoin, but intend to upgrade the current Bitcoin protocol. For this reason they are not going to implement replay protection.
What is replay protection?
After a Bitcoin split there are two seperate blockchains. If the SegWit2x fork will result in a split everyone who owned Bitcoin at the moment of the split will own the same amount of coins on both blockchains. If Bob sends 1 Bitcoin to Alice on the legacy chain, an attacker can copy that transaction onto the SegWit2x chain and cause Bob to send 1 Bitcoin2x on that chain as well. Replay protection prevents such an attack.
Which Bitcoin version will miners mine?
This is a very important question. At this moment about 82% of the current Bitcoin miners show their intention to mine the SegWit2x coin and the other 18% of the miners don't seem to support SegWit2x and will continue to mine the current version of Bitcoin. You can find the most recent percentages on coin.dance. So it looks like a large majority of the miners will stop mining Bitcoin Core (or Bitcoin Legacy or just Bitcoin) and switch to the SegWit2x blockchain. Period. Bitcoin Core is dead and SegWit2x will be the real Bitcoin. Really? Will 82% of the miners really switch to the SegWit2x blockchain after a split? They currently only flag an intention to mine SegWit2x.
Which coin would you mine of you were a Bitcoin miner?
In the end Bitcoin miners are mining for just one reason: profit. Mining cryptocurrencies takes a lot of energy and is therefore very costly. Each miner has to pay his energy bills and eventually they just wants to earn money. It's as simple as that. A miner can choose to mine a certain cryptocurrency to support that blockchain for a while, but if the coin he is mining isn't worth much he will eventually switch to another coin.
According to SegWit2x futures on Coinmarketcap.com the B2X coin will be worth about 21% of BTC. If this will be the actual price of B2X after the split it is very unlikely 82% of the Bitcoin miners will continue to mine B2X. It will be very unprofitable while mining BTC will be much more profitable due to the drop in hashrate on the BTC chain. If I were a Bitcoin miner I would, without a doubt, switch to the most profitable coin which will surely be BTC.
The Bitcoin miners may act as if they are in control of the system, but it is the market that sets the price for a coin due to supply and demand. Most Bitcoin exchanges, such as CoinBase, have stated they will continue to list Bitcoin as BTC and will list the new SegWit2x coin as B2X. Moreover, it's hard to find Bitcoin users who support the SegWit2x hard fork. When everone start selling their B2X coins for more BTC the B2X coin has definitely lost the game.
B2X will be an unusable cryptocurrency due to the lack of replay protection. No one dares to use the coin for fear of losing real Bitcoin (BTC). It will first lose its value, then its miner support and will eventually die off.
