I'm pretty sure Hussie is playing this for keeps, and the Trolls are getting their character growth out of the way before getting nixed. A few may carry over, but I suppose it's entirely possible that their arc ends in a complete tragedy, and the kids will be working to set things right from there.
Even after the dream self extra lives are exhausted, the dead aren't exactly gone. Aradia was a ghost, and used to speak to other ghosts before she became one. Feferi appeared in one of Jade's bubble dreams, and said that she was there because she was dead. Dream Jade returned with stories from beyond. Kanaya is currently missing and presumed to be stalking the tunnels of the laboratory complex, thirsty for blood and romance. I guess they might all be red herrings, carefully planted by Andrew to conceal his true motives, but it sure seems that there are a lot of ways you could bring the dead trolls back to life.
Feferi's bubble appearance kind of implies that the dead live on, in some sense or another, beyond the Furthest Ring. If Rose is planning to travel there in search of the Green Sun, does that mean that the dead could travel
out? I think that would be such a delicious callback. The Problem Sleuth walk-out-through-death's-front-door resurrection mechanic dressed up in mystique, dream prophecies and elder gods.