I won't go into what I think about Ann Coulter... But the sad fact is that we do need you just as much as you need us. The day the borders close you can be sure that both countries will suffer more than anybody think. For a lot of different things we are your natural ressource warehouse and for a lot of others a cheap and fast manufacturing destination. The US exports around 90 billions worth of goods to Canada each year, and we export 250 billions worth back to you, you think you can replace that kind trade overnight? Not likely. Sure it could be done with time but a lot of jobs would be lost and the economy would crumble beforehand.
Besides, the rollover comment is not typically American, you guys are not colonialists, you get in, hit hard, appoint somebody of supposed trust then get out.