I had an issue with my heated bed today where the thermistor had become partially detached, causing the actual temperature to increase in a way which did not trigger any protection.
In industry it is common to have some redundancy for temperature measurements. I would like to attach a second thermistor to my heated bed and have Klipper behave as follows:
If the temperature difference between them is greater than x for y seconds then shutdown printer,
else use the average of the two values.
For the ultimate in redundancy it would be possible to use three sensors, where if one value strays out of range of the others then it is removed from the calculation but the printer stays in service. This may be worth implementing, however it would have limited practical usage without means of alerting the user to the failed sensor.