I think you can do both. I think you can rejoice over a force for evil going away while also recognizing that some of those forces are still human and could still be redeemed. The fact that anybody, even the most evil person, would ever spend a literal eternity being destroyed without perishing is a terrifying concept to think about regardless of whether or not that eternal destruction and separation is self-inflicted.

Moreover, one can still find salvation in the final seconds of their life if God wills it. The thing is, we ultimately don't know a person's salvation. Ours is the only one that can be believed in confidently, but I'm certain that Christ has revealed Himself to many on their deathbed.