Well, goodness - here I thought we were talking about a single state making incremental moves, vice a full-blown national shift.United States Consumer Spending | 1950-2015 | Data | Chart | Calendar
US Consumer Spending was 11.2T or so
US total Income Tax is around 2.2T
On its face, that's about a 19.7% Consumption Tax needed to remain revenue neutral.
That would be a net tax increase for at least 60% of households
Historical Average Federal Tax Rates for All Households
But yes, you'd need a consumption tax around there, dependent on how you structured it. Which would indeed raise effective rates for the majority of households - that's why the Fair Tax folks have the Prebate, to make their policy more progressive than the current structure, by making all spending up to the poverty line tax-free.