I don't agree with the model.
Far too many assumptions and far too many extrapolations. As an engineer, I understand the dangers of going beyond current knowledge and applying regional coefficients beyond that region.
Simply wrong. Now, the magnitude of how wrong it is might be worth discussion...
The model does extrapolate to the end of the century. Any engineer would ignore anything beyond twenty years since the present worth calculation at twenty years is the same as at infinity. As a practical matter, twenty years is project lifetime.