What happens if it failes?
It will and it'll maybe chaotic.
It fails one way or another. Market will melt down too.
Quote this as a note of someone who bashes BitcoinXT. Maybe this is what they want.
I assume readers are smart enough to figure out who supports Core, who supports XT, and who doesn't know yet. For example, meono seems to have recently made his account just for the purpose of pushing XT. Not that there's anything wrong with that. And LiteCoinGuy clearly supports XT and is trying to downplay the risks that come with a hard fork that many people oppose.
My account is new for a reason, but its not what you believe . If it bothers you too much PM Mods or Admin to find out...