Which is a shame because if they waited one more expansion, he would have had the perfect job for him : Reaper.
A job whose history is linked with a people who can't use aether and decided to make contract with voidsents to get around their magical limitations.
It's even stated that Reaper were silent assassins which would fit Thancred too.
It would have been a natural progression from his rogue days, to stay a stealthy DPS, hiding in the shadows.
And he has gone in Garlemald multiple times, he could easily have picked the job there instead of gunbreaker.