What would happen is that Wal-Mart and Amazon, et al. would pay their fair share of taxes, and the owners (or share holders) would not be multi-billionaires, only single-digit millionaires at most. The effect would be that every single person in the United States would have Heath Care, Tertiary Education paid for, excellent unemployment benefits, etc. etc.
There would no longer be desperate people struggling to survive while others have orders of magnitude more money than can be spent in 10 lifetimes.