Re: if we knew of our death ahead of time.
In some ways, it would be a relief to know the exact timeline so one could plan each chapter better and live it up a little more (because things are more certain and clear cut now). And in some ways, some uncertainty would still exist (like accidental death ... from plane crashes, car accidents, bomb blasts, gang fights etc.); I'm assuming here that these situations can still arise regardless of the auto shut off mode being in place. Right?
If we knew for sure that we will live up to 80 regardless of our life choices (bold or risk averse) and that we will die a natural death, life would be a lot less risky and perhaps a little boring because of it.
You can compare it to married life vs. singlehood. In a lifelong marriage with the same spouse, there is stability and comfort but also boredom at times. In a single life with multiple or no companion (your choice), there is more adventure and independence but also the possibility of dissatisfaction.