If Hillary Clinton becomes President and we are still in Iraq, she will deliberately lose the war early on in her presidency because she will believe that she can blame it on George Bush. That will allow her to avoid taking on a politically unpopular war. The result of her actions would likely be a huge victory for Al-Qaeda, genocide, an enormous loss of American prestige, and a crisis of confidence in our military.
Disaster In The War On Terror: When Bill Clinton was in power, the 2nd Intifada started, Al-Qaeda launched terrorist attacks at America practically with impunity, he turned down an offer of Sudan to hand over Osama Bin Laden, Pakistan and India built nuclear programs right under our noses -- and we believe North Korea built nuclear weapons.
If Hillary were to become President, expect North Korea to become a permanent nuclear power, Iran to start a nuclear arms race in the Middle East, and Al-Qaeda to get a breather to rebuild their forces because Hillary will be more concerned with whether Europe likes us or not than stopping another 9/11.
Additionally, she would certainly curtail the wiretapping of terrorists and would treat them as mere criminals instead of unlawful combatants, which would significantly hurt our intelligence gathering and make another 9/11 much more likely.
Socialized Medicine: If Hillary Clinton gets her way and we have socialized medicine in this country, taxes will soar, the quality of medical care will decrease, and the wait times to get surgeries will grow enormously.
Supreme Court: Currently, the Supreme Court is balanced on a knife's edge. There are 4 originalist judges who believe in sticking to the Constitution, 4 liberal judges who view the Court as nothing more than a Super Legislature than can be used to push a left-wing agenda, and one moderate judge.
That means the Supreme Court nominees of the next President of the United States will likely tip the balance of the court dramatically to the left or right and with Hillary, of course, you can be sure that the judges would be extremely liberal.
We don't know who the Republican nominee will be yet, but whoever he is would have to be an enormous improvement over the massive head-on car crash in an earthquake that a Hillary Clinton presidency would be for America.