Collector current vs. temperature
Just for your understanding: The base emitter voltage does NOT decrease if the temperature (and with it the collector current) are increasing.
The sequence is as follows: For a constant VBE voltage the collector current Ic increases for higher temperatures of the transistor body (increased carrier mobility). And the bias voltage VBE must be externally reduced (2mV/K) in order to bring Ic back to the former value (that is the background saying Ic=constant). This VBE reduction should be done automatically by applying voltage feedback (emitter resistorRE).