Originally Posted by
Fullblod
They can replace you with a person that hasn't killed any boss heroic in Firelands this week, true.
If they kill Ragnaros, those 10 players will be saved + you. You participated in the first 6 bosses which means you all now share the same heroic ID, so now 11 people are saved in that heroic ID to a cleared instance.
It may however say in your raid info that Ragnaros is still alive and well, but he ain't. This happen to us long ago when we were going to do Sinestra and saw that the pug we found had made a group of his own before us and killed her.