Okay, so I'm subbing for a graphic novel class this mod, and I've got a stack of comics that I hand out in class every week. One of them is the Marvel Essential Mighty Thor, vol. 1. Now, I had never read Donald Blake's introduction before, so I figured I'd take the ten weeks to read through the whole collection.
Mush to my surprise, pages four and five of the first issue, Donald Blake finds the old, gnarled staff in a cave, smacks it on a rock and then transforms into Thor.
Let me reiterate that for everyone:
He becomes Thor.
Now, this is important. Donald Blake doesn't cease to exist. He's still Donald Blake, but he's also Thor. He possesses the power, and the identity, of Thor.
So here's the interesting thing about the new Thor: there was a fairly vocal contingent when she was announced that spoke ill of the character, saying that just because you pick up the hammer, that doesn't make you Thor.
However, comic book continuity is a murky thing at the best of times. It can be rewritten, ignored and brought back at a moment's notice. The whims of the studio and the writers dictate what is and isn't canon.
So here's my take on the new Thor: she picked up Mjolnir and became Thor. It's that simple. Just because Thor still exists doesn't make the new Thor any less the character by comparison. He's still him, but he was just born Thor. He's Thor Odinson, one of many Thors down throughout the ages, according to Odin's eye.
The new Thor, much like Donald Blake before her, grasped the hammer and became the God of Thunder. She is Thor, and anyone who argues otherwise clearly doesn't understand the character's roots.