GQ recently interviewed Poe Dameron himself, Oscar Isaac, where he reveales that Poe was originally meant to die in the early scripts of The Force Awakens. Check out the quotes:
“He opens the whole movie!” said Abrams.
“Sounds great!” thought Isaac.
“And then,” Abrams went on. “He dies.”
“Oh,” thought Isaac.
“I’d done that before,” he told me later. “Set up the plot for the main guy and then die spectacularly.” (He had played just such a role in The Bourne Legacy.)