god, i actually kind of hate that. i dunno. i could learn to like it. i won't mind if he ends up just being, like, an old version of the eighth, because the eighth doctor has had so much mythology built up around him because he only ever had the one appearance, and i always took it as read that it was the eighth doctor who fought and ended the time war, or that the eighth died during the time war and the ninth finished it off, which is why he was so dark underneath the smiling jester act. having another whole incarnation - "the real ninth doctor" - between the two kind of diminishes nine's gravitas.
granted, it raises some interesting questions - did hurt's doctor die at the end of the time war? before? why would universal prophecies about the doctor fail to take into account his 'missing' regeneration? if this missing doctor was so crucial and pivotal during the time war, regardless of whether the doctor wants to forget him, how did the universe let him? does that mean "the fall of the eleventh" was ten's death? does he have only one regeneration left then (which is even further muddied by the imprecise science of river song "gifting" her remaining regenerations to bring the doctor back to life back in season six -- did he get leftover regenerations from that?)?
I DUNNO. VALEYARD WOULD BE COOL. this seems like "well, we couldn't get christopher eccleston, so check it out there's this 'lost doctor' we've never mentioned before. also the ninth doctor is actually the tenth, the tenth doctor is the eleventh, and all the puns we've made surrounding the number eleven during matt's run are actually kind of nonsensical because he is really the twelfth".
i did see a photo of hurt in a costume that appeared to be a hybrid of eight and nine's (had nine's leather jacket under a long victorian-style dress coat), also.