I strongly doubt they will replace the sensors, maybe it's influence the hardware in a 2nd version but they have plenty of sensors in the current Nest protect.

I strongly doubt they will replace the sensors, maybe it's influence the hardware in a 2nd version but they have plenty of sensors in the current Nest protect. It's more of a matter of better measuring the room to allow the unit to guess when someone is walking by and when someone is standing in front of the unit and waving. The sensors are almost working perfectly. Because this device is relied upon to save peoples lives and there are also legal repercussions to allowing a known bug, they have to make sure that the waving and walking can be distinguished 100% of the time. Only in a very rare situation (like having the unit at shoulder level or in a hallways with a very low ceiling combined with multiple people running past it) would the unit malfunction.