The only way that I can see that we end up with two chains is if the fork occurs without consensus. With BitcoinXT, the fork is programmed to occur with consensus, therefore that fork becomes BTC. If it occurs without consensus (which is what NotBitcoinXT is doing) then we will end up with two chains and both BTC and BXT will be discredited and then both will crash and die.
This is simply wrong. XT is programmed to fork with 75% support of the hash rate, but that is not consensus, not even among miners. Even more importantly, the miners are not what actually counts here. It is the users and the "economic majority" that is often quoted recently.