Now, I know that a lot of people want flood for Firefight (Myself included) but I think that if they are introduced, they wouldn’t be very numerous. Like the ODST on Instillation 04. Maybe they could be the maps hazards, like a lot of combat and infection forms spilling over the map boundries. Because, (I’m not an expert, so I don’t KNOW) but I don’t think the Reach engine could support flood now. The game was used with the skeleton of the Halo 3 engine, but I think the flood was removed so the game could be expanded more. That and flood didn’t join the fight until a few days after Halo: Reach.
So, they would be AMAZING, but if they are added now, I’m not too sure that they would be that amazing, seeing as they are, more then likely, not at all supported.
Sad, I know. But hey! There’s halo 4 coming next year, there’s nothing to suggest that the flood won’t be in Firefight then!