I think the real "life expectancy" of the 2016 MBP will be ... how much longer the butterfly keyboard keeps working.
It's now too old for the 4-year extended warranty for the keyboard.
If the keyboard has a failure now -- even if it's only FOR JUST ONE KEY -- it's going to run at least $750 to get it working again, since the entire top case needs to be replaced (again, even for only one key).
Next to this, "software" that's running on it is... inconsequential.