Consider this scenario: thermal destruction might mean a complete meltdown, when silicon turns polycrystalline, i.e. conductive, so most likely all terminals will be conductively connected inside the transistor itself.

However, in this situation, the current flowing through base may (depending on circumstances) rise to a point when the base bond burns through (which is usually much weaker than the emitter bond, whereas collector is formed by the dice itself glued to the case/frame base). So, the base contact on the dice is conductively conected to emitter/collector, but the base pin is disconnected.

I think I have seen all combinations of shorts and disconnects, and even detrimentally decreased beta (presumably as a conseqence of partial meltdown), on low-voltage-high-current power transistors in heavy-metal TO-3 (I was repairing some rather old equipment like ultrasonic bath, back then in the school).

JW