With a win against NYG, the worst possible record for Dallas is 9-7. With NY taking the loss, their best possible record would be 8-8. Best possible record for Philly is 8-8.
A win at Philly is only meaningful if the Giants lose to the Jets next weekend, in which case it would clinch the division. But assuming a Giants win, a loss at Philly does not impact the Cowboys chances of winning the division.
It's an interesting scenario and it helps me sleep better at night, since I fear the Eagles game much more than the Giants game.
I only post this because everything I read seems to suggest that the Eagles game is a must-win for the Cowboys.