That is not, however, what the chart in TFA shows. It shows the bottom 5th percentile with income going down, and income gains increasing in relative (as well a

That is not, however, what the chart in TFA shows. It shows the bottom 5th percentile with income going down, and income gains increasing in relative (as well as absolute) terms as you get higher up the income percentiles. FWIW income inequality is normally reported proportionally (using the Gini coefficient or something similar) so even in your hypothetical case inequality would be reported as constant rather than increasing.