In part
...but that seems like a legitimate thing for a historian to do, as presumed experts in the history being extrapolated. Certainly anyone else who attempts to extrapolate history from a shakier base could produce only shakier extrapolations.
Where we really differ is in our faith that Bush can bring about this outcome:
My prediction. When Iraq becomes a democracy, and freedom takes over the Middle East, he’ll probably be seen as one of the greatest presidents.
To me, that's not a "when", it's a huge "if", based on Bush's performance so far. I personally believe that Bush's actions and policies have actually made it harder to achieve those worthy goals. We agree on on a hypothetical positive outcome, but disagree completely over Bush's potential to be the agent of those developments.
A second area with which I take issue is the implication in your statement that the end justifies the means. If Bush ever achieves those ends, history will also judge how he got there, and will evaluate that course against other potential courses that might have involved more or less bloodshed and trauma. History's judgment might be, in a sense, regretful: A worthy outcome, but a terrible and unnecessary price to pay. It's possible to win a battle and still lose the war.
In a related vein, a third point is to take your unquantified description of a positive outcome and anchor it to reality by considering the price. If America is damaged in the course of achieving a worthy outcome for others, can one really rate the American President who did it a success? We all want America to be a force for good in the world, but we can't accomplish that good if we destroy the instrument by which we hope to achieve it. The idea is to achive a net overall gain in good on a global scale. Doing good in the Middle East but destroying America is a net loss.