It means getting out the vote. And while blacks and Philly were the winning card for Barak, this is NOT the same game.
It's not so quite as bad as that when you look at Independents too. As of April 2016 here is how registered voters broke out in PA:
Democrats = 4,062,187
Republicans = 3,126,166
Other = 1,085,350
When you add the Republicans and Independents (Other) together, the Dems are outnumbered. Now obviously one can't assume that 100% of "Other" will vote Republican but there will be a good number of Democrats voting Trump in PA, especially in coal country and in blue collar areas. The state is definitely winnable for Trump. As you say, it's all about the turnout.
Here in Connecticut, where Trump signs are exploding across neighborhoods everywhere, we are in even better position to pull off an upset.
Connecticut - November 2015
Democrats = 776,886
Republicans =429,301
Other (Independents) = 900,669
Wow! Combining Republicans and "Other" in CT and you have not a virtual tie as in PA but a 553,084 advantage!
Getting Republican and Independents to the polls in CT could very well produce a surprise Trump victory here.