ballscrewbob:
Each component has a different lifespan depending on quite a lot of variables.Voltage, Current, Operating Temperature range, Memory writes (both V and Non V and EEPROM vs EPROM), Humidity, and a few more besides.
The only way to know is for YOU to work out what that is as you have given zero detail in any of that regards and it is simply beyond the scope of the forum to do that work for you.
Then use your application of those figures as a measure of how far you will be pushing each of those items and use the shortest lifespan as a very basic MTBF.
I think he was "assuming" that the MTBF analysis was done.
Otherwise, his company would have pay for it themselves if such an analysis is important to their customer base.
.