Within the very richest segment (those with an income elasticity of consumption approaching zero) VAT would become almost flat (as a percentage of consumption) or somewhat regressive (as percentage of income). Given the ability of the superrich to evade income tax, the net effect of VAT would still be progressive even at the superrich level.
Shane Mage
> This cosmos did none of gods or men make, but it
> always was and is and shall be: an everlasting fire,
> kindling in measures and going out in measures."
>
> Herakleitos of Ephesos