We had this vehicle since 2007 and it never gave us any trouble. Last Saturday while on the highway with our entire family in the car it just caught on fire. We were able to pull over and within minutes the entire car was engulfed in flames. Has this been an issue with these cars?
No. Some 185,000 2006 and up Trailblazers had a recall for bad wiring on the drivers door but yours isn’t included. And it IS 15 years old, after all.
I’ve had three of them and frequent the boards associated with the platform (Trailblazer/Envoy/Ascender). There hasn’t been any indication of self immolation on any, let alone a mass extinction event, that I have seen… 
Sorry to hear of your troubles, has anyone determined what caused the fire?
I’m guessing a fuel line sprung a leak in the engine compartment. Similar fate happened to my '65 Mustang that had been passed on to my brother in law.