" it gets worse"
Not as dire.
As the temperature goes up, the power being dissipated also goes up. This leads to slower rise in temperature, everything else being equal.
The net impact is that for some transistors they will reach thermal equilibrium. Otherwise, you would have any working transistors now.
The opposite is also true: with the right combination, any bjt can be driven into thermal run away by a ccs.
Not as dire.
As the temperature goes up, the power being dissipated also goes up. This leads to slower rise in temperature, everything else being equal.
The net impact is that for some transistors they will reach thermal equilibrium. Otherwise, you would have any working transistors now.
The opposite is also true: with the right combination, any bjt can be driven into thermal run away by a ccs.