Not a huge concern. It's using a registered voter model that will naturally far outdo typical Democratic turnout.
More importantly the bulk of the undecideds are in central and northwest PA.
Unless Republican hacks have an effective campaign of voter suppression that makes new registration nearly impossible and get away with it... in Presidential elections, a "registered voter" model is closer to reality than a "likely voter" model. There remains no evidence that there won't be a large number of new voters in Pennsylvania.
Remember -- Mitt Romney still has a 7% gap to make up in Pennsylvania, and that won't be easy in a D-leaning state.
In Pennsylvania, by registration, 51% of voters are Democrats, but in any election, only about 42-44% of the voters are.
It's not a fast growing state in population, nor are there massive new sources of young people here.
Pennsylvanians did have babies between 1990 and 1994,
How do Pennsylvanians have babies?
The ruffed grouse brings them to couples.
