When flying into a 1x1 whole with Elytra, you get suffocated and you die. You cannot escape.
(Confirmed with a .gif file)

To reproduce:
1. Make a 10x10 wall that is 1 block thick.
2. Break block so you have all blocks are diagnol, but not touching. (Make 1x1 holes between each block.)
3. Build a tower near by and stand on top of it.
4. go into survival and fly toward a hole.
5. Hold shift as you near the hole.