> For the rich (defined here as anyone with enough wealth that, if they don't spend it down, they will face estate taxes) they either have to realize the gains (and be taxed) and spend down or leave an estate which will be subject to estate taxes, giving them a maximum time window on taxation equal to their lifespan.

It would be if not for the "estate tax holiday" we have periodically which together with a bunch of other ways of avoiding the estate tax is why it only constitutes a negligible amount (0.6%) of federal revenue.

The fundamental problem with the estate tax is that it's a huge tax that happens with semi-unpredictable timing, which induces rich families to do estate tax planning to avoid having liquidity problems when it happens. But "estate tax planning" means paying fifty million dollars to tax lawyers and lobbyists to avoid paying a billion dollars in estate taxes.

In practice what it means is that rich families will do much more to avoid and lobby against the estate tax than they would against a tax that collected the same amount of money from them but more predictably over a longer period of time. Which makes it a losing proposition if your goal is to get the rich to pay taxes.

> Because it also changes the cost structures on which debt is occurred, this only is meaningful as a one-time effect on debts that exist at the time of the transition to a predominantly-consumption-tax system, not as durable feature.

It applies equally to the interest paid on the existing debt. And given that the total interest generally exceeds the principal (and exceeds it moreso for poorer people paying higher interest rates), the "one time effect" would be with us for a generation or more.