It won't happen. Sean's star was really just beginning to rise when he met George - and it's been going down since then. He can't compete against the likes of Crowe and Bale, who have had non-stop starring roles for the last three years . . . while he was busy dissing the folks who give you jobs.
Talent doesn't count for squat; it's all about box office draw - and yes, WE know that Sean COULD draw an audience, but who is going to give him the chance when they have sure things on call?
He started "nesting" and got comfortable and complacent? *shrugs* Like I said. If he doesn't have the ambition...
Anyway. There's quite a bit of discussion on the IMDb forums of "Nottingham" on Who should play Robing Hood and quite a lot of support for the boy as well as opinions that he is too old for the part.
I don't think he's too old for the role - it actually makes more sense to have an older Robin Hood - particularly if they are going with the deposed Earl who rode off on Crusade with the Lionheart, etc, etc. The little fella they have on the BBC television version is what, twelve? And yet he was supposed to have been off on Crusade for three years? The Children's Crusade, maybe . . .
Even if they go with the other version of RH - the yeoman turned bandit without a redeeming quality (none of the merry men or "giving to the poor" - he just kept it), there's no reason an older man couldn't play the role.
Russell Crowe is five years younger than Sean and doesn't look particularly sprightly (imo - not bad. doesn't float my boat), and he is presumably playing the love interest to Sienna Miller (at least it's the Middle Ages, when young women were married off to old farts all the time . . .) - it might actually play into the idea of an "evil" Robin Hood if he were played by an older man - someone grizzled and a bit world weary and cynical. It always strains credulity when they have a young person trying to convince the audience that they're world weary and cynical.
But I really do not think that they will cast Sean. I think his "nesting" (love the euphemism!) has actually damaged his reputation in the business and he's paying the piper now. It may not be a lack of ambition as much as a series of bad choices and now the roles he wants just aren't coming his way. Let's face it - the projects that he's been attached to (even speculatively) for the last couple of years are either hold-overs from before he started his slide into mediocrity (like AWONI and CLS) or small budget indies (like TROAE) or scripts that sound suspiciously like "B" movies.
Last Battle Dreamer has some potential - but it could also turn out (if it every gets made) to be one of those weird modern love stories set in the past, so it all looks very contrived and silly and ends up going straight to DVD and Sunday afternoon showings on the the movie channels.
Black Death has all the hallmarks of the classic "B" bloody, scary, horror flick - there's potential there, but when you see the word "necromancer" it doesn't really suggest a plot of any depth.
That's not to say he wouldn't make some money from them - there are plenty of people who love that stuff. But he won't earn any more credit in "serious" acting circles - and since he has apparently squandered what he did have, he needs at least a little if he ever wants to have a chance at a major production or a film with a shot at critical acclaim. If he lacks ambition, then I suspect he doesn't care - if he does care than I feel very sorry for him - but he made his bed.