Turnout needs to be big in rural PA, but it’s not impossible. The Pittsburgh area has been gradually trending Republican for a while. NR just released a lengthy explanation:
http://www.nationalreview.com/article/438269/donald-trump-pennsylvania-path-white-house
Also, though completely anecdotal, when I drive around Western PA, I see lots of Trump signs in yards and in buildings, even in some of the towns that I would have expected would lean Democrat. I occasionally would see a Bernie bumper sticker (never a sign). Not once have I ever seen a Hillary sign or sticker.