The wealthy already avoid many taxes. I don't think Bitcoin will make that much difference in tax avoidance. Taxes will still be collected on purchases at regular business and possibly when cashing out Bitcoin.
i think that is not the solid reason , in fact bitcoin is killing the income tax but in future when the governments will consider bitcoin as legal currency then they will impost income tax on bitcoin and i think then bitcoin will be the most income tax generating currency of the world.
If it comes to that then I think some bitcoin tax havens will exist already and will allow you with the tools already in place to put a company in one of those countries and pay no tax if that is what you want.