Impractical and impossible are of course two different things. It's sort of funny to consider a scenario in which a manufacturer adds a thermistor to the speaker coil assembly to measure the temperature & lower the amplifier output via the BIOS as the temperature in the voice coil rises to a dangerous level. I suspect that might cost more than using good speakers in the first place but then again if there's limited room for speakers which would lead to heat buildup in the voice coil such a solution might be practical.