Actually, yeah. While I don't think his death in Ultima Thule would have much impact, his sacrifice in Ahm Araeng would have been the best moment to kill the character if they wanted to. I can't recall Ryne's growth since then being dependent on Thancred's presence either, which means it wouldn't impede her development as a character.
Likewise as much as I'm sick of Y'shtola's flanderization and boring goals the right windows for sacrificing her were missed, so at this point she'd be another one I'd prefer was just sidelined instead. Which of course, won't happen either.