In all seriousness, it's very hard to say. He may be an unpopular President now, but he did liberate two countries, crush the Taliban, cripple al-Qaida, put nuclear inspectors in Libya, Iran and North Korea, without firing a shot, and captured a terrorist who slaughtered 300,000 of his own people.
He did accomplish a lot, despite how the public currently view him. A lot of people hated Lincoln when he was in office, and look at how history views him now: considered to be one of the greatest American Presidents in history.
Not saying Bush will go down like Lincoln did, but you never know. We'll have to wait a while to find out.