So, did Hillary Clinton win or lose tonight? Well, that depends on your definition of "win". She certainly did win PA. Unfortunately, she isn't running for President of PA. She's running for the presidency of the United States.
In that endeavor, she's lost big time. Here's why:
Hillary is currently losing in pledged delegates:
Obama: 1415.5
Clinton: 1253.5
Hillary is currently losing in combined pledged/super delegates:
Obama: 1646.5
Clinton: 1508.5
She has to catch Obama in delegates. The numbers do shift a little, but ultimately, she needs to make up about 150 delegates.
Pennsylvania represents ~28% of remaining pledged delegates. In order for her to get back on track, she needs to pick up 42 delegates from PA (and that's assuming she can pull off the same percentages in ALL future states - states where Obama currently enjoys a double digit lead). If you want to get realistic about how many delegates she needs out of PA considering how she will do in future races, it's impossible. Chuck Todd is saying that Hillary's ceiling of possible delegate pickups from PA is about 18.
The headlines tomorrow should read "Hillary Clinton Wins Pennsylvania, Loses Democratic Nomination"
It's over. And it has been for some time.