I am sure all you experts are correct in what you say about the natural degradation and the dangers of overuling this on the life span of the battery.
I am just a poor ignoramous that cannot believe that the batteries are naturally degrading at the rate that is being seen.
What i do believe is that Mitsubishi should be more customer service orientated and include in their service schedule a check on the real state of the battery, not just rely on the guesses by its software/firmware, and have the ability to restore the battery capacity in the software/firmware to what it actually is so that the owner can always get the maximum electric drive as they expected when they spent the extra money on buying a PHEV. They could also consider updating their software/firmware so that it is more accurate in its guess.
Without this we might just as well have bought a "self charging hybrid" and saved the money.