In casting The Three Musketeers, your first priority is D'Artagnan. He needs to be good-looking and uncomplicated. It helps if he doesn't look a complete buffoon with a fussy moustache and beard. And if he is completely incapable of expressing moral shades of grey, that's all to the good. Proven ability to buckle swash is also a plus.
Yes, Orlando Bloom is obviously your man. But no one has copped to this. The Percy Jackson kid (of whom I have no knowledge, nor any care to know) will be D'Artagnan.
What makes it much, much worse is that Orlando Bloom is actually in the movie. As the Duke of Buckingham.
Did anyone read the book? Orlando Bloom can certainly not play a world-weary Lothario. He could barely get Kirsten Dunst into bed in Elizabethtown; his chances with Anne of Austria seem slim. He might be slightly too old to play a really perfect D'Artagnan, but that's everyone else's fault for holding off too long on the film.
It's probably impossible to make a plausible movie of The Three Musketeers, because books by Alexandre Dumas are absurd and ridiculous. But that doesn't mean you shouldn't try, and doesn't mean you should ignore gifts when they fall into your lap. Idiots.
For good measure, Orlando Bloom should also remake any and all Errol Flynn movies. Especially Captain Blood. And not the weird General Custer one.