You've got to hand it to Hillary Clinton. The rumours of her death were greatly exaggerated. I think it has to be worrisome for Obama because she came back by attacking him and he can't really say that the attacks were unfair. What is his message? What are we hoping for? What is this Change? What's revolutionary about him other than his multiply hyphenated identity?
He can be whatever you want, but if you cast yourself as everyone's mirror, you run the risk that someone will turn it back on you. Running as the "new kind of candidate" who "transcends the politics of the past" may win a primary or two, but it grows old fast. See, e.g., John Anderson, Gary Hart, Paul Tsongas and Bill Bradley. There is a reason that politics is like it is and chances are that you were not sent by God to change that.
I think that the rest of the campaign is still about him. If he can articulate some kind of message that at least seems to have some substance, Hillary will not be able to hold her support. In that sense, the race is still his to win or lose.