this is how it works alreadyPlayers A, B, C and D queue for a dungeon.
Player D falls asleep.
The queue pops, players A, B and C click accept, and player D does not.
The queue fails. The dungeon finder takes the next-in-priority DPS from whatever group they are in, places them in the group, and re-pops the instance. Players A, B and C get their "average" queue time pop, plus a little bit extra for the failed player D, instead of potentially 4 to 5 times the "average" queue timer depending on their luck.