VAT would help but you cant replace the income tax without having catastophic consequences to the infrastructure of the country.
Rich pay their share of taxes. When you hear of them putting money into "tax free" or "tax friendly" investments, they are given the tax break so that we (the county, locola govt. etc,) can use their money for our betterment.
Example; The M exhange here in Milwaukee.
The state, county, and City all paid for the M exchange (for those not from milwaukee, it was a massive two year improvement of the highway interchange right downtown Milwaukee.
Well, The cost was about 2 billion (guess). Since there wasnt enough cash flow to support it, they needed to borrow from someone. No banks, have that kind of cash to lend (at least not to one risk). So they borrow from the general public in the form of a muni bond issue.
Muni bonds are available for anyone to purchase, even you and me. As a reward for investing back into the economy, tyou get your returns state income tax free and sometimes federal, and sometimes completely tax free. .
Wiht out that incentive (flat tax, VAT) there would be a loss of available capital for growth. That would be bad.