They do continue living as spirits, but they do not get the chance to have another mortal body. They miss out on the one and only chance to live in this mortal existence. They also miss out on all of the life's experiences that they would learn from. They'll get a body some day, but it would be a resurrected perfect body like that of Christ's. All of the things that they miss out on from not getting to live this life will have to be made up some other way.
They point is though that they wanted to come down here and live this life. They waited an eternity to do it and now they'll never get this experience again. They'll never get to know what it's like to be mortal, make mistakes, learn from them, make ourselves better. And we miss out on all of the good or bad things they could have brought to us. We have to face up to those people in the next life as well, and explain why we thought it was so much more important for us to kill them, than to let them have this one experience on earth, the same that we got to have. People simply do not know what they're doing. If they did, I'm sure things would be different. Therefore, may God be merciful to us all.
Those are my beliefs on the topic.
Aaron2