It doesn't get much worse than that to be honest.
Also starring Taylor Lautner as Harry's partner, Sam Worthington as the villain, Lindsay Lohan as a Romanian prostitute (and Harry's love interest) and Adam Sandler as Harry's precinct captain. Written by Eli Roth and Paul Haggis.
Okay, that's a pretty extreme take on it (except maybe Paul Haggis), and it probably wouldn't happen because while Hollywood is very good at shooting itself in the foot, studios don't do it intentionally.
The reason why I listed an Abrams-Ratner-LaBeouf collaboration is simple: it's the kind of move Hollywood would actually make. Abrams would produce, because he makes "good" films like SUPER 8 (but he basically tried too hard to be Steven Spielberg, and it showed), was "responsible" for
Lost (though he only wrote two episodes) and has successfully rebooted the STAR TREK franchise (it was pretty boring, but I'll give him that one). Ratner would direct, because he's handled franchises before, like THE LAST STAND and RUSH HOUR (but they're all rubbish), and he's also firmly established in the crime/thriller genre with films like TOWER HEIST and RED DRAGON (which are also rubbish). And Shia LaBeouf would be cast because the studios would no doubt want someone young, who could stay with the franchise for a while (but he's just a terrible actor). Paul Haggis would probably write the script because he deals with political issues - but he's at the opposite end of the spectrum to Harry's character, so it would be a bit like QUANTUM OF SOLACE when he had James Bond accuse the Americans of being imperialists when Bond himself represents England's interests, which were often imperial in nature, since he is a defender of the realm.
So while this film would look good on paper, it would ultimately suffer because the entire thing was geared towards making a "good" movie rather than a DIRTY HARRY movie. No doubt the focus groups and test audiences would respond positively to te individual elements, but as a whole it would just falter horribly.
For a DIRTY HARRY reboot to work, you would need a studio who understands what the character is all about. First of all, you would need an R-rating. If there is no R-rating, there is no film. If fifteen year-olds can't get into see it, that's too bad. DIRTY HARRY hasn't been on-screen in nearly twenty-five years, so there is a whole host of mature-age audiences who can make the film a success without needing the teenage male demographic. Secondly, you would need a screenwriter who understood the character and the films - they would need to idenfity them and retain the common elements. The basic storyline would be pretty easy; say, for example, an extortionist poisons toothpaste (or something that everyone needs and uses) and holds San Francisco to ransom. While Harry's superiors treat it as a conventional blackmail case, Harry becomes convinced that the killings are not as random as first thought (half of them could be witnesses to a string of drive-by shootings and the other half random victims to muddy the waters), and the film goes from there. But the script would need to be true to the character. Then you would need a director, someone who understands the conventions of the crime thriller. I'd suggest Ben Affleck (hopeless actor, incredible director) or Nicolas Windig Refn (who made the excellent DRIVE). Then comes the actor best-suited to the role (though no-one immediately springs to mind), and finally, you would need Clint Eastwood's blessing. Once you got all of that right, then you would have a Hollywood reboot/remake that would not suck.