A fire in flight would lead to bus failure and depressurization very quickly.
Its pretty obvious that a fire will LEAD to bus failure. It will also LEAD to the person sitting in row 40 to get his feet burned.
If there's a fire onboard a plane, warning systems almost immediately detect it and warn the crew. The crew would have plenty of time to make MANY radio calls. Just like ValueJet in the Everglades did, and that thing turned into a roman candle at 11,000 feet in 1 minute.
Unless you want to throw into the mix that a flame-thrower behind the captains seat accidentally went off in the cabin. Then I'll go along that the bus failed from the fire........... lol