This would require significant tax treaty changes. http://www.crossborderalliance.com/Resources/NRA%20Tax%20gui... has some of the basics of how it works.

Essentially, this has major consequences on foreign investments which were built on the assumptions of a individual tax.

Further, there are trusts that can limit tax burdens. It is quite possible that the total taxation would decrease, and it would decrease on those at the top of the heap, not at the bottom.

We would have to figure out how to rebalance. Consider this a refactoring on code that is not easily unit testable.