Interesting thoughts all around. I've definitely had non-PC death consequences for failure. Things like the BBEG escaping, Capturing PC's, Important Objects being stolen, Rituals being completed, etc.
This leads into a further question: Does a loss-spiral have negative impacts on the campaign?
Loss-spirals are a made-up name meant to represent a situation where a previous loss compounds on to a future loss. For example, a ritual being completed might make a certain powerful devil appear or the capturing of PC's land them in the center of the dungeon of the enemy with no resources recovered.
How do you feel about these loss-spirals?