Pennsylvania is surely “in play.” If the GOP can win it somehow, they win the White House. If they lose Pennsylvania, along with every state that had a smaller GOP percentage vote in 2012 than Pennsylvania had, they lose the White House. Just like its nickname implies, Pennsylvania is the Key stone for this election.
That’s not to say GOP victory is impossible without Pennsylvania. If the election is close, you may assume that GOP will take North Carolina, Ohio, and Florida. Given those states and Virginia, they’d only need one more swing state; it wouldn’t have to be the Keystone State. Tiny New Hampshire would push them over, as would any of Colorado, Iowa, Nevada, Minnesota, or Wisconsin. (With neither Pennsylvania nor Virginia, the GOP would probably have to win at least three other swing states.)
TL;DR: Don’t let your guard down. November 2016 still looks like a coin-toss. Complacency in Pennsylvania would be a huge mistake.